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Identification of symptoms for spasmodic dysphonia and vocal tremor: a comparison of expert and nonexpert judges
Journal of Communication Disorders 34 (2001) 21 ± 37
Identification of symptoms for spasmodic dysphonia and vocal tremor: a comparison of expert and nonexpert judges Julie M. Barkmeiera,*, James L. Caseb, Christy L. Ludlowc a
Department of Speech and Hearing Sciences, University of Arizona, P.O. Box 210071, 1131 East Second Avenue, Tucson, AZ 85721, USA b Arizona State University, University Drive and Mill Avenue, Tempe, AZ 85287-0102, USA c Laryngeal and Speech Section, National Institute of Neurological Disorders and Stroke, Bethesda, MD 20892, USA Received 28 March 2000; received in revised form 2 August 2000; accepted 2 August 2000
Abstract Spasmodic dysphonia is a rare voice disorder that is most successfully treated by injection of botulinum toxin (i.e., BOTOX) into the affected laryngeal muscles. BOTOX is currently available for use by professionals outside of metropolitan voice centers who may be unfamiliar with this rare disorder. Patients may seek assessment and treatment locally from clinicians who are unfamiliar with the speech symptoms for adductor-type (ADSD) or abductor-type (ABSD) spasmodic dysphonia. Although these disorders have been described in the literature, the symptoms have not been well defined and may appear similar to those of vocal tremor or muscle tension dysphonia (MTD). Thus, patients with spasmodic dysphonia might not be easily identified by local clinicians for treatment. The purpose of the current study was to determine whether voice clinicians with infrequent exposure to patients with spasmodic dysphonia could learn to identify speech symptoms for ADSD and ABSD comparable to voice clinicians with extensive experience with these disorders. The ratings of five nonexpert judges were compared to the ratings obtained from three expert judges. The results of this study demonstrated that nonexpert judges could be trained to identify the speech symptoms associated with ADSD, ABSD, and vocal tremor. While the nonexpert judges tended towards false positive judgements for the speech symptoms of interest, the overall speech symptom profiles for each type of voice disorder appeared comparable to those obtained from the expert judges. The symptom identification * Corresponding author. Tel.: +1-520-621-5699; fax: +1-520-621-9901. E-mail address: [email protected] (J.M. Barkmeier). 0021-9924/01/$ ± see front matter D 2001 Elsevier Science Inc. All rights reserved. PII: S 0 0 2 1 - 9 9 2 4 ( 0 0 ) 0 0 0 3 9 - 3
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scales used, therefore, have potential for use by clinicians unfamiliar with these disorders for correctly identifying persons with symptoms of ADSD and ABSD. Educational objectives: Readers will be able to (1) define the predominant speech symptoms reflective of the voice disorder categories of ABSD, ADSD, and vocal tremor; and (2) describe the methods utilized in a new perceptual training protocol for teaching clinicians how to identify predominant speech symptoms associated with the voice disorder categories of ABSD, ADSD, and vocal tremor. D 2001 Elsevier Science Inc. All rights reserved. Keywords: Spasmodic dysphonia; Vocal tremor; Evaluation
1. Introduction The speech symptoms for adductor-type (ADSD) or abductor-type (ABSD) spasmodic dysphonia have been described in the literature (Aronson, Brown, Litin, & Pearson, 1968a, 1968b; Leonard & Kendall, 1999; Ludlow & Connor, 1987; Nash & Ludlow, 1996; Rodriquez, Ford, Bless, & Harmon, 1994; Shipp, Izdebski, Reed, & Morrissey, 1985). Although the literature discusses the typical presentation of symptoms for ADSD and ABSD, individuals with these rare disorders may often exhibit additional symptoms that are similar to that of vocal tremor or muscle tension dysphonia (MTD). Clinicians less familiar with spasmodic dysphonia, therefore, may not be well acquainted with the varied presentation of symptoms of this voice disorder. Thus, patients with spasmodic dysphonia might not be identified for treatment when clinicians are not familiar with the disorder. Currently, there are no standardized methods for instructing clinicians to properly identify and describe the various symptoms that best characterize ADSD, ABSD, vocal tremor, and MTD. The literature offers several descriptors of symptoms for each type of voice disorder (Aronson et al., 1968a, 1968b; Leonard & Kendall, 1999; Ludlow & Connor, 1987; Nash & Ludlow, 1996; Rodriquez et al., 1994; Shipp et al., 1985); however, these voice symptom descriptions may not be adequate for instructing clinicians who have not encountered persons with each of these voice disorders. A standard method for training clinicians to identify hallmark perceptual characteristics associated with ADSD, ABSD, and vocal tremor could facilitate improved identification of each type of disorder leading to improved clinical assessment and treatment recommendations. In order to develop such a training tool, it is important to consider the typical speech patterns associated with each type of voice disorder. 1.1. Adductor-type spasmodic dysphonia ADSD is a voice disorder characterized by a strained ± strangled voice quality and intermittent voice stoppages, or breaks associated with overadduction of the vocal folds (Aronson et al., 1968a, 1968b; Leonard & Kendall, 1999; Ludlow &
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Connor, 1987; Nash & Ludlow, 1996; Rodriquez et al., 1994; Shipp et al., 1985). These voice breaks typically occur during speech associated with voiced speech sounds and during sustained phonation in moderate to severe cases of the disorder (Ludlow & Connor, 1987; Sapienza, Walton, & Murry, 1999). Stressful speaking situations may exacerbate speech symptoms while they appear absent, or reduced in severity during such activities as laughing, throat clearing, coughing, whisper, humming, and falsetto speech productions (Aronson et al., 1968a, 1968b; Ludlow & Connor, 1987). 1.2. Abductor spasmodic dysphonia Abductor spasmodic dysphonia is characterized by intermittent breathy breaks associated with prolonged abduction of the vocal folds during voiceless consonants in speech (Aronson et al., 1968a, 1968b; Leonard & Kendall, 1999; Rodriquez et al., 1994). These voice breaks typically occur during speech associated with voiceless speech sounds (Ludlow, Naunton, Terada, & Anderson, 1991). Similar to ADSD, symptoms of ABSD may worsen during stressful speaking situations and lessen in severity or remain absent during such activities as laughing, throat clearing, coughing, whisper, humming, and falsetto speech productions (Aronson et al., 1968a, 1968b). Individuals with ADSD and ABSD may attempt to prevent their symptoms by increasing the tension in their laryngeal muscles in an effort to compensate for their symptoms. The consequence is the addition of symptoms similar to MTD along with spasmodic dysphonia. The overriding symptoms of MTD can escalate over time such that the underlying symptoms of ADSD are difficult to discern. It has also been observed that spasmodic dysphonia may co-occur with vocal tremor (Aronson & Hartman, 1981; Ludlow, Bassich, Connor, & Coulter, 1986). In such cases, it is important to characterize the tremor component as well as the symptoms of spasmodic dysphonia. 1.3. Vocal tremor Vocal tremor is characterized by periodic fluctuations in the voice frequency or intensity at a rate between 3 and 12 Hz (Gamboa et al., 1998). These perceived fluctuations in the voice may be associated with periodic modulations of the laryngeal structures as well as other structures of the vocal tract. Tremor of the laryngeal structures is usually at 5 Hz and may be isolated to speech, but may also occur during quiet breathing (Koda & Ludlow, 1992). In severe cases, vocal tremor can be perceived during connected speech. However, identification and characterization of vocal tremor is best determined from sustained voicing of a vowel sound (Ludlow, 1995). Other patterns associated with vocal tremor include reduced magnitude during softer or high-pitched voice productions. Similarly, vocal tremor magnitude increases during louder voice productions. With severe vocal tremor, voice
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stoppages may occur such that these individuals exhibit symptoms similar to ADSD or ABSD. In addition, individuals with vocal tremor may attempt to prevent tremor from becoming apparent by increasing the tension in their laryngeal muscles. As a result, the compensatory increase in effort results in the addition of MTD to the vocal tremor. 1.4. Muscle tension dysphonia MTD refers to individuals with voice dysfunction that is not associated with abnormalities of the laryngeal structures (Morrison, Rammage, Belisle, Pullen, & Nichol, 1983). Rather, these individuals exhibit excessive muscular tension while speaking. In addition, they may also display a reduced range of motion in one or more articulators, overactivity in the extrinsic laryngeal musculature during speech, abnormal vocal fold approximation, and a pressed or strained voice quality (Aronson, 1990; Roy, Ford, & Bless, 1996). Views of the larynx using videoendoscopy may demonstrate the presence of a posterior or anterior glottal gap during sustained phonation in these individuals. Morrison et al. (1983) also described the potential for emotional factors to be involved in the manifestation of voice problems demonstrated in this group. Current clinical methods for assessing individuals with these four voice disorders combine information from the case history, videoendoscopic views of the larynx, and perceptual judgements of speech samples. Recent research has attempted to characterize various acoustic and physiologic parameters for each of these voice disorders (Callan, Kent, Roy, & Tasko, 1999; Gamboa et al., 1998; Higgins & Chait, 1999; Leonard & Kendall, 1999; Sapienza et al., 1999). However, perceptual judgements of the occurrence of the different types of voice symptoms continues to be the standard for identifying individuals with symptoms of ABSD, ADSD, and vocal tremor. Based on the current understanding of perceptual attributes for ADSD, ABSD, vocal tremor, and MTD, a perceptual speech symptom assessment protocol was developed to identify the speech symptoms exhibited by patients who have ADSD, ABSD, and vocal tremor. The current protocol differs from the traditional perceptual methods in that clinicians score the number of occurrences of specific speech symptoms characteristic of the voice disorders of interest (e.g., adductor voice breaks, abductor breathy breaks, and tremor). The speech material used was designed to elicit speech symptoms characteristic of each type of voice disorder. The final scores for the speech symptoms provide a speech symptom profile that can help determine whether the patient exhibits speech symptoms typical of one of the voice disorders of interest. It is important to determine whether clinicians with limited experience with spasmodic dysphonia can be trained to correctly identify corresponding speech symptoms. The purpose of this investigation was to determine whether clinicians with limited experience with spasmodic dysphonia (i.e., nonexpert judges) could be trained to accurately identify speech symptoms characteristic of ADSD,
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ABSD, and vocal tremor similar to the performance of those considered expert judges of these voice disorders. 2. Methods 2.1. Voice disorder subjects Speech samples of 20 adults enrolled in a research protocol at the National Institutes of Health were recorded onto a digital audiotape. No identifying information was provided on any of the subjects including their name, age, sex, or geographic location. The primary investigator selected the 20 subjects to include 4 representative subjects in each of five diagnostic categories: (1) ABSD, (2) ADSD, (3) vocal tremor, (4) MTD, and (5) normal controls. All recorded subjects used for this investigation previously underwent examination by an otolaryngologist to assess laryngeal structure and function following informed consent to participate in an IRB NINDS-approved protocol. The recordings of those selected for the perceptual portion of the study met the following criteria for each category of voice disorder. (a) The normal controls had normal voicing patterns and no history of neurological abnormalities. (b) The ABSD subjects all exhibited intermittent breathy breaks associated with prolonged voiceless speech sounds (e.g., s, f, th, p, t, k, h), a history of gradual onset of symptoms over several months, and exacerbation of symptoms under stress. These subjects' symptoms were present for 1 year or more. (c) The ADSD subjects exhibited intermittent voice stoppages associated with hyperadduction of the vocal folds. Perceptually, the voice breaks/stoppages were glottal stops or intermittent strained ± strangled periods during vowel productions. These subjects had a history of gradual symptom onset over several months, exacerbation of symptoms under stress, and presence of their symptoms for at least 1 year. (d) The vocal tremor subjects had periodic fluctuations in pitch and/or loudness during sustained phonation of /a/ and on vowel sounds during connected speech. (e) The MTD subjects had a consistently ``pressed'' or tense voice quality during connected speech. These individuals also reported no change in symptoms with stress and no intermittent ``islands'' of normal connected speech. 2.2. Acoustic recordings All subjects were recorded using a standardized instructional stimulus tape. The stimulus tape provided subjects with uniform and consistent instructions and
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provided examples of each requested speech production. During the recording session, subjects were instructed to sustain the vowel, /a/, for at least 6 s at a comfortable pitch and loudness and to produce the following sentences: (a) The puppy bit the tape. (b) We mow our lawn all year. (c) The dog dug a new bone. (d) Did he go to the right or to the left. (e) When he comes home we'll feed him. Subjects were recorded while sitting comfortably with a Shure unidirectional microphone placed 5 cm directly in front of their mouth. Speech signals were preamplified (homemade preamp) and recorded to digital audiotape (DAT) using a Sony DTC 690 data recorder. All samples were recorded at a rate of 10 kHz. 2.3. Perceptual raters 2.3.1. Expert judges Three judges had at least 5 years of specialized clinical and/or research experience with spasmodic dysphonia and vocal tremor. This involved one evaluation of at least 36 patients ABSD, ADSD, and vocal tremor per year. The expert judges performed the perceptual speech symptom identification protocol in a different location independent from the nonexpert judges. Expert judge rating sessions took place in a quiet room while listening to subject recordings no more than 3 ft from two audio speakers. The expert judges first refined the scoring sheet (Appendix A) and then listened to the subject speech stimuli. They counted and rated the samples without undergoing the training protocol described below for the nonexpert judges. When greater than 20% discrepancy occurred in scoring, the judges listened to the sample again and each re-rated one sample. However, if disagreements continued, the judges did not alter their scores after the second rating. 2.3.2. Nonexpert judges Five nonexpert judges with an average of 16.4 years of clinical experience with voice disordered populations (ranging from 8 to 26 years) volunteered to participate as nonexpert judges. These individuals differed from the expert judges in the frequency of clinical exposure to individuals with symptoms of spasmodic dysphonia. The nonexpert judges reported experience with assessment of one to five patients exhibiting symptoms of spasmodic dysphonia per year (average of 3.2 per year). All of the judges were familiar with BOTOX treatments and had observed them previously. All of the judges who agreed to participate conveyed prior interest in learning how to correctly identify the speech symptoms characteristic of spasmodic dysphonia compared with other voice disorders.
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2.4. Perceptual rating tape 2.4.1. Experimental tape The 20 subjects recordings selected for this study were randomly recorded onto a high quality cassette tape using a Sony HX Pro tape recorder. Each subject recording consisted of sustained /a/ followed by the five sentence productions. 2.4.2. Training tape An audiotape consisting of one subject for each of the five diagnostic categories served as a training tape prior to use of the experimental tape. The subjects chosen for the training tape differed from subjects selected for the experimental tape described above. The training tape examples were judged by the primary investigator to provide clear examples of hallmark speech patterns characteristic of ABSD, ADSD, MTD, vocal tremor, and normal control speech. The first two authors reached consensus on the occurrences of each type of speech symptom within the speech samples on the training tape. These scores were used as the ``expert scores'' for the training session of the study. That is, the training tape was used for the purposes of teaching the nonexpert judges how to score the occurrences of each speech symptom across the different types of voice disorders. 2.5. Perceptual rating protocol The perceptual speech symptom identification required raters to score the number of occurrences of specified parameters (defined below) for each speech sample using the rating sheet displayed in Appendix A. Unlimited playback of each sentence recording was allowed to insure that raters had adequate opportunity to accurately tally the number of speech symptom occurrences. 2.5.1. Speech symptom scoring Each subject recording began with sustained /a/ followed by the sentence recordings. Upon completion of the sustained /a/ recording, raters were instructed to rate whether periodic oscillations in pitch and loudness indicative of tremor were perceived. If raters perceived such a fluctuation, they were instructed to determine whether it was consistently or intermittently present in the sustained vowel recording. The level of tremor severity was rated as 0 (normal), 1 (intermittent), 2 (draws attention to itself), or 3 (interferes with intelligibility). Next, raters listened to each of the sentence productions and tallied how many occurrences of the following occurred: 1. Voice breaks on vowels (VB): These were defined as voice stoppages, glottal stops, or breaks in ongoing sound and could be associated with an interval of a strained ± strangled voice quality. Voice breaks typically
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occurred on voiced speech sounds such as in the sentences, ``We mow our lawn all year,'' and ``The dog dug a new bone.'' 2. Breathy breaks (BB): These were defined as sudden breathy bursts or prolongation of voiceless consonants (s, f, th, p, t, k, or h) during connected speech. Breathy breaks typically occurred on voiceless speech sounds such as, ``he'' and ``to the'' in the sentence, ``Did he go to the right or to the left?'' on ``The puppy'' and ``tape'' in the sentence, ``The puppy bit the tape,'' and on ``comes home'' and ``feed him'' in the sentence, ``When he comes home we'll feed him.'' 3. Tremor (TRE): This was defined as a periodic modulation in the voice perceived during production of a vowel during connected speech. Tremulous vowel production was best perceived during more prolonged vowel productions such as occurred during the sentences, ``We mow our lawn all year,'' ``The dog dug a new bone,'' and ``When he comes home we'll feed him.'' 2.5.2. Predominant speech symptom scoring After all of the speech samples were scored and the total number of occurrences of each type of speech symptom was determined, both the expert judges and the nonexpert judges were instructed to select the category of voice disorder representative of the predominant speech symptom. The nonexpert judges were given the following criteria for selecting from the listed voice disorder categories identified by the expert judges: 1. Subjects with larger scores for adductor voice breaks than abductor breathy breaks and fewer occurrences of vocal tremor were assigned to the category of ADSD. 2. Subjects with larger scores of abductor breathy breaks than adductor voice breaks and fewer occurrences of vocal tremor were assigned to the voice disorder category of ABSD. 3. Subjects scoring a larger total of occurrences of vocal tremor were to be assigned to one of the types of vocal tremor listed. AD tremor was defined as the presence of vocal tremor with a voice quality that was perceived as pressed, or tense. AB tremor was defined as the presence of vocal tremor with a voice quality that was perceived as breathy. 4. MTD was selected when the subject had a consistent voice quality abnormality and few voice breaks, breathy breaks, or occurrences of vocal tremor. 5. WNL represented a speech sample that was judged to be within normal limits on all voice symptom parameters. 6. Subjects judged to have large numbers of both voice breaks and occurrences of vocal tremor were assigned to ADSD + Tremor. 7. Similarly, ABSD + Tremor was assigned to subjects with large numbers of both breathy breaks and of vocal tremor.
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The final selection of the voice disorder category was used to determine whether nonexpert judges correctly determined the predominant speech symptom present in a given subject speech sample. 2.6. Nonexpert listening sessions The nonexpert listening sessions took place on two occasions separated by no more than 1 week. The first listening session consisted of the training task (approximately 1 h) followed by 1 1/2 h of the experimental rating task. The second session began with a review of the training tape anchor samples and continuation of the experimental rating task (approximately 2 1/2 h). The training task taught the nonexpert judges how to use the speech symptom parameter portions of the rating sheet. In addition, one recording of sustained /a/ and one set of five sentences for each of the five types (VB, BB, Tremor, MTD, and WNL) were presented to judges for practice using the perceptual assessment protocol. Judges participated in groups of 2 ±3 individuals seated within 3 ± 4 ft of two Optimus speakers in a quiet room. Judgements were based on acoustic recordings played at comfortable loudness as determined by the participating judges. 2.7. Data analysis The total number of instances of VB, BB, TRE, and vocal tremor for each subject was recorded by each judge for comparison. The ``correct'' number of occurrences of each speech symptom was defined as the mean total score obtained for each speech symptom type scored by the expert judges for each subject. Using the mean of the expert judge scores for each subject, the percent of exact agreement, the percentage within one point, and the percentage within two points of exact agreement were determined for the nonexpert judge scores. Repeated within subject ANOVAS were computed to test whether there were significant differences between the expert vs. the nonexpert judges in the mean numbers of voice breaks, breathy breaks, and vocal tremors identified. Because three comparisons were computed, a Bonferroni correction was used for the criterion alpha level ( P =.05/3=.016). The percent of exact agreement for the voice disorder category selected for each subject by the nonexpert judges was compared to that from the expert Table 1 Proportions (%) of agreement for expert judge scores with the average expert judge scores Type of agreement
Voice breaks
Breathy breaks
Occurrences of tremor
Exact Within 1 point Within 2 points
82 88 98
90 98 98
83 87 97
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Table 2 Proportions (%) of agreement for nonexpert judge scores with the average expert judge scores Type of agreement
Voice breaks
Breathy breaks
Occurrences of tremor
Exact Within 1 point Within 2 points
54 66 78
73 80 86
54 65 74
judges. This determined the accuracy of the nonexpert judges in identifying the predominant symptom types for each subject. To determine the ability of each of the individual nonexpert judges to identify each symptom type, listwise Pearson correlation coefficients were computed between the mean of the expert judge symptom counts and each nonexpert judge's symptom counts for each of the three symptom types. 3. Results The expert judges demonstrated high reliability with subject speech symptom scores within one point of exact agreement on 91% and exact agreement on 85% of the subject speech stimuli (Table 1). For selection of the predominant speech symptom associated with each voice disorder category, expert judges were in 100% exact agreement. One of the subjects selected by the primary investigator as having a predominant speech symptom consistent with ADSD was rated as MTD by all of the expert judges. This subject was, therefore, recategorized as having a predominant symptom type consistent with MTD. The agreement between averaged expert judge and nonexpert judge scores for each type of speech symptom is shown in Table 2. As can be seen by these data, the exact agreement for the same number of occurrences of each speech symptom
Fig. 1. Mean numbers of symptoms counted by the expert (shaded squares) and nonexpert judges (filled black circles) for each of the 20 subjects for vowel breaks (on the far left), breathy breaks (in the center), and tremor breaks (on the far right).
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Table 3 Comparison of nonexpert to expert judge scores for the predominant symptom type across subjects Nonexpert frequencies for each predominant symptom type Predominant symptom type
Expert counts
ADSD
ABSD
Vocal tremor
MTD
WNL
Nonexpert counts
ADSD ABSD Vocal tremor MTD WNL
9 12 12 16 12
14 2 1 3 0
1 16 1 0 0
0 1 17 2 1
0 1 1 20 0
0 0 0 0 19
15 20 20 25 20
There was 100% expert judge agreement for each category with a maximum N of 12 possible, except for the ADSD and MTD categories. The maximum N for each category for the nonexpert judges is 20, except for the ADSD and MTD categories. One of the subjects selected by the primary investigator as having the predominant symptom of ADSD was scored as MTD by the experts.
between judge groups was high. The proportion of agreement between and within the two groups was highest on breathy breaks for both sets of judges. The agreement between the counts for each of the subjects by the two groups of judges for each of the symptom types is shown in Fig. 1. To determine whether the designated categories that expert and nonexpert judges identified for each subject were the same, Table 3 shows the distribution of nonexpert and expert judges' categories for the predominant voice disorder category. As seen in this table, the nonexpert judges were in agreement with expert judges on 86 of the 95 classifications. Thus, the nonexpert judges learned to determine the predominant symptom type present in each subject similar to that identified by the expert judges. The mean numbers of speech symptoms of each type were compared between the two groups of judges on repeated ANOVAs within subjects between the mean scores for the two sets of judges. No significant difference ( P .016) in the number of breathy breaks or vocal tremors were found between judge groups. However, there was a significant difference between expert and nonexpert judge Table 4 Average speech symptom parameter frequencies obtained from nonexpert (NE) and expert (E) judge scores Voice breaks
Breathy breaks
Predominant speech symptom
E
NE
E
NE
Tremor MTD ADSD ABSD WNL Total
0.8 (1.1) 0.6 (0.8) 7.2 (1.9) 0 (0) 0 (0) 1.3 (2.7)
3.1 (4.2) 0.5 (0.8) 10.8 (5.9) 0.3 (1.2) 0 (0) 3.0 (5.2)
0.2 (0.4) 0 (0) 0 (0) 7.6 (2.1) 0 (0) 1.6 (3.2)
1.0 0.1 0.2 10.1 0.1 2.1
The standard deviation is displayed in parentheses.
Vocal tremor (1.7) (0.5) (0.9) (4.5) (0.2) (4.3)
E
NE
7.8 (3.4) 0.9 (1.8) 2.1 (1.6) 0.1 (0.3) 0 (0) 2.1 (3.5)
7.8 0.8 1.3 1.9 0.1 2.4
(4.0) (2.0) (2.4) (3.0) (0.5) (3.8)
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Table 5 Pearson correlation coefficients for each of the nonexpert judges in agreement with the expert judges mean scores for each break type Pearson r Judge
Vowel breaks
Breathy breaks
Tremor breaks
1 2 3 4 5
.909 .838 .587 .923 .819
.850 .967 .684 .873 .949
.813 .624 .954 .836 .754
scores on the number of voice breaks across subjects ( F = 7.68; P = .012) with the nonexpert judges counting more vowel breaks than the expert judges (Table 4). To examine the ability of each of the five nonexpert judges to agree with the expert judges, Pearson correlation coefficients were computed for each of the judges for vowel breaks, breathy breaks, and tremor (Table 5). Different judges were accurate on different symptom types, Judge 3 had poor agreement with the expert judges on vowel breaks and breathy breaks but had good agreement on tremor. Judge 2 had poor agreement with the expert judges on tremor breaks. 4. Discussion The results of this study demonstrated that nonexpert judges learned to identify predominant speech symptoms reflective of the voice disorder categories of ABSD, ADSD, and vocal tremor as compared to expert judges. While 86% exact agreement is an adequate level of agreement, a preferred outcome of such training is 100% agreement between nonexpert and expert judges. Less than 100% agreement with expert judges could relate to possible confusion identifying each of the speech symptoms. For example, nonexpert judges demonstrated 54% exact agreement with expert judges on scoring voice breaks and occurrences of vocal tremor across subjects. Correct identification of these speech symptoms is necessary for correct identification of the predominant symptom type. As indicated in Table 4, nonexpert judges more frequently scored subjects as exhibiting voice breaks than did the experts. In addition, the predominant speech symptom type was incorrectly chosen in 14 cases by the nonexpert judges. There did not appear to be a consistent error across the various predominant speech symptom types chosen erroneously by nonexpert judges. Nor was there any particular nonexpert judge who demonstrated a consistent error in selecting the predominant speech symptom type. Thus, uncertainty in choosing the predominant speech symptom type varied across subjects and nonexpert judges. Some non-expert judges, however, may not have learned to accurately identify voice symptoms. This was particularly the case for nonexpert Judge 3 for voice breaks and Judge 2 for tremor breaks.
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One hour of training was completed with nonexpert judges prior to participating in the experimental phase of the study. During this 1-h training session, only one example of each voice disorder category was presented. The training session is vital for providing instruction and practice time to nonexpert judges. Without adequate training time, nonexpert judges may not learn to accurately identify each type of speech symptom associated with ADSD, ABSD, vocal tremor, or MTD. Future work in this area may require more than 1 h for training nonexpert judges. Informally, nonexpert judges frequently commented that the training tape did not adequately prepare them for the variety of speech symptom presentations across the experimental subjects. Thus, future training sessions need to offer a wider variety of examples for each type of voice disorder and allow nonexperts more opportunities to practice identification for each type of speech symptom. Another possible factor for consideration relates to the typical clinical evaluation of individuals with ADSD, ABSD, and vocal tremor. The perceptual speech symptom identification protocol focused the attention of raters on particular speech symptom parameters in the absence of further information about each subject. Clinically, information related to patient history, conversational speech patterns, and laryngeal imaging could influence scores obtained using the current speech symptom identification protocol. While expert judges did not have access to such information for their rating sessions, nonexperts may benefit from the addition of such information. The addition of client history and laryngeal images might be expected to facilitate improved scores. An argument could also be made, however, that such additional information may interfere with judges being able to focus on speech symptoms. In addition, the literature indicates that the best method for accurately determining whether an individual exhibits ADSD or ABSD is through correct identification of the predominant speech symptom type as addressed in this study (Leonard & Kendall, 1999; Ludlow & Connor, 1987). Thus, the contribution of client history and laryngeal images to correct identification of the predominant speech symptom may be negligible. The current perceptual speech symptom identification protocol utilized a combination of speech tasks that was previously determined to best elucidate perceived speech symptoms for ADSD, ABSD, and vocal tremor. That is, sustained phonation of a vowel is the best method for determining the presence of a vocal tremor. Speech samples loaded with glottal stops and voiceless consonants help differentiate between ADSD and ABSD. The current method for scoring the number of occurrences of each type of speech symptom is different from previous methods using traditional rating scales of voice quality. For example, traditional rating scales such as the GRBAS address general voice quality and do not offer a means for scoring specific speech symptoms such as voice breaks, breathy breaks, or vocal tremor. The current method is specifically designed to assist in correctly identifying speech symptoms typical of individuals with ADSD, ABSD, and vocal tremor. The speech samples and organization of the perceptual speech symptom identification protocol would require clinicians to utilize a standard speech protocol for assessment of ADSD, ABSD, and vocal tremor. The use of this
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protocol may help nonexpert judges learn how to more accurately identify the speech symptoms most prominent in the voice disorder populations of interest. All of the nonexpert judges in this study informally commented that they learned how to appropriately test individuals with ADSD, ABSD, and vocal tremor. Perhaps over repeated application of this perceptual assessment protocol, the current nonexpert judges will improve their speech symptom identification scores. Additional investigation of nonexpert judge performance over repeated application could address questions regarding the average learning curve before nonexpert judges perform equally to expert judges. Based on the individual differences in nonexpert judge agreement with the expert judges, it could be argued that some persons require more training time than others and that training should allow for such individual training needs. Overall, the current comparison between nonexpert and expert judges using the perceptual speech symptom identification protocol indicates that this instrument may be useful for training voice clinicians to successfully identify speech symptoms characteristic of ABSD, ADSD, and vocal tremor. Additional investigation needs to be completed to determine the contribution of repeated use of this training protocol for improving speech symptom identification performance.
Acknowledgments We would like to acknowledge Kimberly Bidus and Laura Purcell for their assistance with the development of the rating sheet used as well as their part in conducting the expert judge rating sessions. Shrita Squire's contribution to dubbing the rating tapes is gratefully acknowledged. Appendix A. Subject #:_____________ Rater:_____________ Tremor rating scale: 0 = normal 1 = mild (or intermittent) 2 = moderate (draws attention to itself) 3 = severe (interferes with speech intelligibility) Tremor: Continuous:_______Overall rating:_______________ Intermittent:______ Vowel breaks Breathy breaks Tremor: The puppy bit the tape. _______ _______ _______
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We mow our lawn all year. The dog dug a new bone. Did he go to the right or to the left? When he comes home we'll feed him. Total:
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_______
_______
Predominant symptom type: (circle one) ADSD ABSD AD tremor AB tremor ADSD/ABSD + Tremor Other ADSD/ABSD plus Other WNL Appendix B. Continuing education Identification of symptoms for spasmodic dysphonia and vocal tremor: a comparison of expert and nonexpert judges Questions 1. The predominant speech symptom for adductor-type spasmodic dysphonia is: (a) vocal tremor (b) intermittent breathy breaks (c) consistently pressed voice quality (d) intermittent voice stoppages (e) high-pitched voice 2. The predominant speech symptom for abductor-type spasmodic dysphonia is: (a) vocal tremor (b) intermittent breathy breaks (c) consistently pressed voice quality (d) intermittent voice stoppages (e) high-pitched voice
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3. The best speech task for determining whether a vocal tremor is present is: (a) sustained phonation of a vowel (b) repetition of sentences containing primarily voiced speech sounds (c) repetition of sentences containing primarily voiceless speech sounds (d) spontaneous conversation (e) counting from one to twenty 4. The perceptual training protocol utilized in this study: (a) required raters to score the number of occurrences of each type of speech symptom rather than the traditional method of rating voice quality (b) did not combine perceptual ratings of speech recordings with information obtained from patient history information and laryngeal imaging (c) required raters to determine the presence and consistency of a vocal tremor during sustained phonation of a vowel (d) utilized both sustained phonation of a vowel and connected speech samples to score the number of occurrences of each speech symptom (e) all of the above 5. Compared to expert judges, this study demonstrated that nonexpert judges: (a) were in agreement with expert judges on 86 of the 95 predominant voice disorder category (b) demonstrated significantly different average scores across all speech symptom types compared to expert judges (c) demonstrated 100% agreement with expert judges on all of the predominant speech symptom types (d) scored lowest agreement with expert judges on breathy break scores (e) scored similar occurrences of voice breaks to expert judges
References Aronson, A. E. (1990). Psychogenic voice disorders. Clinical voice disorders. An interdisciplinary approach (3rd ed.) pp. 121 ± 123. New York: Thieme. Aronson, A. E., Brown, J. R., Litin, E. M., & Pearson, J. S. (1968a). Spastic dysphonia: I. Voice, neurologic, and psychiatric aspects. Journal of Speech and Hearing Disorders, 33 (3), 203 ± 218. Aronson, A. E., Brown, J. R., Litin, E. M., & Pearson, J. S. (1968b). Spastic dysphonia: II. Comparison with essential (voice) tremor and other neurologic and psychogenic dysphonias. Journal of Speech and Hearing Disorders, 33 (3), 219 ± 231. Aronson, A. E., & Hartman, D. E. (1981). Adductor spastic dysphonia as a sign of essential (voice) tremor. Journal of Speech and Hearing Disorders, 46 (1), 52 ± 58. Callan, D. E., Kent, R. D., Roy, N., & Tasko, S. M. (1999). Self-organizing map for the classification of normal and disordered female voices. Journal of Speech, Language and Hearing Research, 42 (2), 355 ± 366. Gamboa, J., Jimenez-Jimenez, F., Nieto, A., Cobeta, I., Vegas, A., OrtiPareja, M., Gasalla, T., Molina, J. A., & GarciaAlbea, E. (1998). Acoustic voice analysis in patients with essential tremor. Journal of Voice, 12 (4), 444 ± 452.
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Higgins, M. B., & Chait, D. H. (1999). Phonatory air flow characteristics of adductor spasmodic dysphonia and muscle tension dysphonia. Journal of Speech Language Hearing Research, 42 (1), 101 ± 111. Koda, J., & Ludlow, C. L. (1992). An evaluation of laryngeal muscle activation in patients with vocal tremor. Otolaryngology Ð Head and Neck Surgery, 107 (5), 684 ± 696. Leonard, R., & Kendall, K. (1999). Differentiation of spasmodic and psychogenic dysphonias with phonoscopic evaluation. Laryngoscope, 109, 295 ± 300. Ludlow, C. L. (1995). Management of the spasmodic dysphonias. In: J. S. Rubin, R. T. Sataloff, & G. S. Korovin (Eds.), Diagnosis and treatment of voice disorders ( pp. 436 ± 454). New York: Igaku Shoin. Ludlow, C. L., Bassich, C., Connors, N., & Coulter, D. (1986). Phonatory characteristics of vocal tremor. Journal of Phonetics, 14, 509 ± 515. Ludlow, C. L., & Connor, N. P. (1987). Dynamic aspects of phonatory control in spasmodic dysphonia. Journal of Speech and Hearing Research, 30 (2), 197 ± 206. Ludlow, C. L., Naunton, R. F., Terada, S., & Anderson, B. J. (1991). Successful treatment of selected cases of abductor spasmodic dysphonia using botulinum toxin injection. Otolaryngology Ð Head and Neck Surgery, 104, 489. Morrison, M. D., Rammage, L. A., Belisle, G. M., Pullan, C. B., & Nichol, H. (1983). Muscular tension dysphonia. Journal of Otolaryngology, 12, 302 ± 306. Nash, E. A., & Ludlow, C. L. (1996). Laryngeal muscle activity during speech breaks in adductor spasmodic dysphonia. Laryngoscope, 106 (4), 484 ± 489. Rodriquez, A. A., Ford, C. N., Bless, D. M., & Harmon, R. L. (1994). Electromyographic assessment of spasmodic dysphonia patients prior to botulinum toxin injection. Electromyography and Clinical Neurophysiology, 34 (7), 403 ± 407. Roy, N., Ford, C. N., & Bless, D. M. (1996). Muscle tension dysphonia and spasmodic dysphonia: the role of manual laryngeal tension reduction in diagnosis and management. Annals of Otology, Rhinology, & Laryngology, 105, 851 ± 856. Sapienza, C. M., Walton, S., & Murry, T. (1999). Acoustic variations in adductor spasmodic dysphonia as a function of speech task. Journal of Speech, Language and Hearing Research, 42 (1), 127 ± 140. Shipp, T., Izdebski, K., Reed, C., & Morrissey, P. (1985). Intrinsic laryngeal muscle activity in a spastic dysphonia patient. Journal of Speech and Hearing Disorders, 50 (1), 54 ± 59.
Identification of symptoms for spasmodic dysphonia and vocal tremor: a comparison of expert and nonexpert judges Julie M. Barkmeiera,*, James L. Caseb, Christy L. Ludlowc a
Department of Speech and Hearing Sciences, University of Arizona, P.O. Box 210071, 1131 East Second Avenue, Tucson, AZ 85721, USA b Arizona State University, University Drive and Mill Avenue, Tempe, AZ 85287-0102, USA c Laryngeal and Speech Section, National Institute of Neurological Disorders and Stroke, Bethesda, MD 20892, USA Received 28 March 2000; received in revised form 2 August 2000; accepted 2 August 2000
Abstract Spasmodic dysphonia is a rare voice disorder that is most successfully treated by injection of botulinum toxin (i.e., BOTOX) into the affected laryngeal muscles. BOTOX is currently available for use by professionals outside of metropolitan voice centers who may be unfamiliar with this rare disorder. Patients may seek assessment and treatment locally from clinicians who are unfamiliar with the speech symptoms for adductor-type (ADSD) or abductor-type (ABSD) spasmodic dysphonia. Although these disorders have been described in the literature, the symptoms have not been well defined and may appear similar to those of vocal tremor or muscle tension dysphonia (MTD). Thus, patients with spasmodic dysphonia might not be easily identified by local clinicians for treatment. The purpose of the current study was to determine whether voice clinicians with infrequent exposure to patients with spasmodic dysphonia could learn to identify speech symptoms for ADSD and ABSD comparable to voice clinicians with extensive experience with these disorders. The ratings of five nonexpert judges were compared to the ratings obtained from three expert judges. The results of this study demonstrated that nonexpert judges could be trained to identify the speech symptoms associated with ADSD, ABSD, and vocal tremor. While the nonexpert judges tended towards false positive judgements for the speech symptoms of interest, the overall speech symptom profiles for each type of voice disorder appeared comparable to those obtained from the expert judges. The symptom identification * Corresponding author. Tel.: +1-520-621-5699; fax: +1-520-621-9901. E-mail address: [email protected] (J.M. Barkmeier). 0021-9924/01/$ ± see front matter D 2001 Elsevier Science Inc. All rights reserved. PII: S 0 0 2 1 - 9 9 2 4 ( 0 0 ) 0 0 0 3 9 - 3
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scales used, therefore, have potential for use by clinicians unfamiliar with these disorders for correctly identifying persons with symptoms of ADSD and ABSD. Educational objectives: Readers will be able to (1) define the predominant speech symptoms reflective of the voice disorder categories of ABSD, ADSD, and vocal tremor; and (2) describe the methods utilized in a new perceptual training protocol for teaching clinicians how to identify predominant speech symptoms associated with the voice disorder categories of ABSD, ADSD, and vocal tremor. D 2001 Elsevier Science Inc. All rights reserved. Keywords: Spasmodic dysphonia; Vocal tremor; Evaluation
1. Introduction The speech symptoms for adductor-type (ADSD) or abductor-type (ABSD) spasmodic dysphonia have been described in the literature (Aronson, Brown, Litin, & Pearson, 1968a, 1968b; Leonard & Kendall, 1999; Ludlow & Connor, 1987; Nash & Ludlow, 1996; Rodriquez, Ford, Bless, & Harmon, 1994; Shipp, Izdebski, Reed, & Morrissey, 1985). Although the literature discusses the typical presentation of symptoms for ADSD and ABSD, individuals with these rare disorders may often exhibit additional symptoms that are similar to that of vocal tremor or muscle tension dysphonia (MTD). Clinicians less familiar with spasmodic dysphonia, therefore, may not be well acquainted with the varied presentation of symptoms of this voice disorder. Thus, patients with spasmodic dysphonia might not be identified for treatment when clinicians are not familiar with the disorder. Currently, there are no standardized methods for instructing clinicians to properly identify and describe the various symptoms that best characterize ADSD, ABSD, vocal tremor, and MTD. The literature offers several descriptors of symptoms for each type of voice disorder (Aronson et al., 1968a, 1968b; Leonard & Kendall, 1999; Ludlow & Connor, 1987; Nash & Ludlow, 1996; Rodriquez et al., 1994; Shipp et al., 1985); however, these voice symptom descriptions may not be adequate for instructing clinicians who have not encountered persons with each of these voice disorders. A standard method for training clinicians to identify hallmark perceptual characteristics associated with ADSD, ABSD, and vocal tremor could facilitate improved identification of each type of disorder leading to improved clinical assessment and treatment recommendations. In order to develop such a training tool, it is important to consider the typical speech patterns associated with each type of voice disorder. 1.1. Adductor-type spasmodic dysphonia ADSD is a voice disorder characterized by a strained ± strangled voice quality and intermittent voice stoppages, or breaks associated with overadduction of the vocal folds (Aronson et al., 1968a, 1968b; Leonard & Kendall, 1999; Ludlow &
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Connor, 1987; Nash & Ludlow, 1996; Rodriquez et al., 1994; Shipp et al., 1985). These voice breaks typically occur during speech associated with voiced speech sounds and during sustained phonation in moderate to severe cases of the disorder (Ludlow & Connor, 1987; Sapienza, Walton, & Murry, 1999). Stressful speaking situations may exacerbate speech symptoms while they appear absent, or reduced in severity during such activities as laughing, throat clearing, coughing, whisper, humming, and falsetto speech productions (Aronson et al., 1968a, 1968b; Ludlow & Connor, 1987). 1.2. Abductor spasmodic dysphonia Abductor spasmodic dysphonia is characterized by intermittent breathy breaks associated with prolonged abduction of the vocal folds during voiceless consonants in speech (Aronson et al., 1968a, 1968b; Leonard & Kendall, 1999; Rodriquez et al., 1994). These voice breaks typically occur during speech associated with voiceless speech sounds (Ludlow, Naunton, Terada, & Anderson, 1991). Similar to ADSD, symptoms of ABSD may worsen during stressful speaking situations and lessen in severity or remain absent during such activities as laughing, throat clearing, coughing, whisper, humming, and falsetto speech productions (Aronson et al., 1968a, 1968b). Individuals with ADSD and ABSD may attempt to prevent their symptoms by increasing the tension in their laryngeal muscles in an effort to compensate for their symptoms. The consequence is the addition of symptoms similar to MTD along with spasmodic dysphonia. The overriding symptoms of MTD can escalate over time such that the underlying symptoms of ADSD are difficult to discern. It has also been observed that spasmodic dysphonia may co-occur with vocal tremor (Aronson & Hartman, 1981; Ludlow, Bassich, Connor, & Coulter, 1986). In such cases, it is important to characterize the tremor component as well as the symptoms of spasmodic dysphonia. 1.3. Vocal tremor Vocal tremor is characterized by periodic fluctuations in the voice frequency or intensity at a rate between 3 and 12 Hz (Gamboa et al., 1998). These perceived fluctuations in the voice may be associated with periodic modulations of the laryngeal structures as well as other structures of the vocal tract. Tremor of the laryngeal structures is usually at 5 Hz and may be isolated to speech, but may also occur during quiet breathing (Koda & Ludlow, 1992). In severe cases, vocal tremor can be perceived during connected speech. However, identification and characterization of vocal tremor is best determined from sustained voicing of a vowel sound (Ludlow, 1995). Other patterns associated with vocal tremor include reduced magnitude during softer or high-pitched voice productions. Similarly, vocal tremor magnitude increases during louder voice productions. With severe vocal tremor, voice
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stoppages may occur such that these individuals exhibit symptoms similar to ADSD or ABSD. In addition, individuals with vocal tremor may attempt to prevent tremor from becoming apparent by increasing the tension in their laryngeal muscles. As a result, the compensatory increase in effort results in the addition of MTD to the vocal tremor. 1.4. Muscle tension dysphonia MTD refers to individuals with voice dysfunction that is not associated with abnormalities of the laryngeal structures (Morrison, Rammage, Belisle, Pullen, & Nichol, 1983). Rather, these individuals exhibit excessive muscular tension while speaking. In addition, they may also display a reduced range of motion in one or more articulators, overactivity in the extrinsic laryngeal musculature during speech, abnormal vocal fold approximation, and a pressed or strained voice quality (Aronson, 1990; Roy, Ford, & Bless, 1996). Views of the larynx using videoendoscopy may demonstrate the presence of a posterior or anterior glottal gap during sustained phonation in these individuals. Morrison et al. (1983) also described the potential for emotional factors to be involved in the manifestation of voice problems demonstrated in this group. Current clinical methods for assessing individuals with these four voice disorders combine information from the case history, videoendoscopic views of the larynx, and perceptual judgements of speech samples. Recent research has attempted to characterize various acoustic and physiologic parameters for each of these voice disorders (Callan, Kent, Roy, & Tasko, 1999; Gamboa et al., 1998; Higgins & Chait, 1999; Leonard & Kendall, 1999; Sapienza et al., 1999). However, perceptual judgements of the occurrence of the different types of voice symptoms continues to be the standard for identifying individuals with symptoms of ABSD, ADSD, and vocal tremor. Based on the current understanding of perceptual attributes for ADSD, ABSD, vocal tremor, and MTD, a perceptual speech symptom assessment protocol was developed to identify the speech symptoms exhibited by patients who have ADSD, ABSD, and vocal tremor. The current protocol differs from the traditional perceptual methods in that clinicians score the number of occurrences of specific speech symptoms characteristic of the voice disorders of interest (e.g., adductor voice breaks, abductor breathy breaks, and tremor). The speech material used was designed to elicit speech symptoms characteristic of each type of voice disorder. The final scores for the speech symptoms provide a speech symptom profile that can help determine whether the patient exhibits speech symptoms typical of one of the voice disorders of interest. It is important to determine whether clinicians with limited experience with spasmodic dysphonia can be trained to correctly identify corresponding speech symptoms. The purpose of this investigation was to determine whether clinicians with limited experience with spasmodic dysphonia (i.e., nonexpert judges) could be trained to accurately identify speech symptoms characteristic of ADSD,
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ABSD, and vocal tremor similar to the performance of those considered expert judges of these voice disorders. 2. Methods 2.1. Voice disorder subjects Speech samples of 20 adults enrolled in a research protocol at the National Institutes of Health were recorded onto a digital audiotape. No identifying information was provided on any of the subjects including their name, age, sex, or geographic location. The primary investigator selected the 20 subjects to include 4 representative subjects in each of five diagnostic categories: (1) ABSD, (2) ADSD, (3) vocal tremor, (4) MTD, and (5) normal controls. All recorded subjects used for this investigation previously underwent examination by an otolaryngologist to assess laryngeal structure and function following informed consent to participate in an IRB NINDS-approved protocol. The recordings of those selected for the perceptual portion of the study met the following criteria for each category of voice disorder. (a) The normal controls had normal voicing patterns and no history of neurological abnormalities. (b) The ABSD subjects all exhibited intermittent breathy breaks associated with prolonged voiceless speech sounds (e.g., s, f, th, p, t, k, h), a history of gradual onset of symptoms over several months, and exacerbation of symptoms under stress. These subjects' symptoms were present for 1 year or more. (c) The ADSD subjects exhibited intermittent voice stoppages associated with hyperadduction of the vocal folds. Perceptually, the voice breaks/stoppages were glottal stops or intermittent strained ± strangled periods during vowel productions. These subjects had a history of gradual symptom onset over several months, exacerbation of symptoms under stress, and presence of their symptoms for at least 1 year. (d) The vocal tremor subjects had periodic fluctuations in pitch and/or loudness during sustained phonation of /a/ and on vowel sounds during connected speech. (e) The MTD subjects had a consistently ``pressed'' or tense voice quality during connected speech. These individuals also reported no change in symptoms with stress and no intermittent ``islands'' of normal connected speech. 2.2. Acoustic recordings All subjects were recorded using a standardized instructional stimulus tape. The stimulus tape provided subjects with uniform and consistent instructions and
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provided examples of each requested speech production. During the recording session, subjects were instructed to sustain the vowel, /a/, for at least 6 s at a comfortable pitch and loudness and to produce the following sentences: (a) The puppy bit the tape. (b) We mow our lawn all year. (c) The dog dug a new bone. (d) Did he go to the right or to the left. (e) When he comes home we'll feed him. Subjects were recorded while sitting comfortably with a Shure unidirectional microphone placed 5 cm directly in front of their mouth. Speech signals were preamplified (homemade preamp) and recorded to digital audiotape (DAT) using a Sony DTC 690 data recorder. All samples were recorded at a rate of 10 kHz. 2.3. Perceptual raters 2.3.1. Expert judges Three judges had at least 5 years of specialized clinical and/or research experience with spasmodic dysphonia and vocal tremor. This involved one evaluation of at least 36 patients ABSD, ADSD, and vocal tremor per year. The expert judges performed the perceptual speech symptom identification protocol in a different location independent from the nonexpert judges. Expert judge rating sessions took place in a quiet room while listening to subject recordings no more than 3 ft from two audio speakers. The expert judges first refined the scoring sheet (Appendix A) and then listened to the subject speech stimuli. They counted and rated the samples without undergoing the training protocol described below for the nonexpert judges. When greater than 20% discrepancy occurred in scoring, the judges listened to the sample again and each re-rated one sample. However, if disagreements continued, the judges did not alter their scores after the second rating. 2.3.2. Nonexpert judges Five nonexpert judges with an average of 16.4 years of clinical experience with voice disordered populations (ranging from 8 to 26 years) volunteered to participate as nonexpert judges. These individuals differed from the expert judges in the frequency of clinical exposure to individuals with symptoms of spasmodic dysphonia. The nonexpert judges reported experience with assessment of one to five patients exhibiting symptoms of spasmodic dysphonia per year (average of 3.2 per year). All of the judges were familiar with BOTOX treatments and had observed them previously. All of the judges who agreed to participate conveyed prior interest in learning how to correctly identify the speech symptoms characteristic of spasmodic dysphonia compared with other voice disorders.
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2.4. Perceptual rating tape 2.4.1. Experimental tape The 20 subjects recordings selected for this study were randomly recorded onto a high quality cassette tape using a Sony HX Pro tape recorder. Each subject recording consisted of sustained /a/ followed by the five sentence productions. 2.4.2. Training tape An audiotape consisting of one subject for each of the five diagnostic categories served as a training tape prior to use of the experimental tape. The subjects chosen for the training tape differed from subjects selected for the experimental tape described above. The training tape examples were judged by the primary investigator to provide clear examples of hallmark speech patterns characteristic of ABSD, ADSD, MTD, vocal tremor, and normal control speech. The first two authors reached consensus on the occurrences of each type of speech symptom within the speech samples on the training tape. These scores were used as the ``expert scores'' for the training session of the study. That is, the training tape was used for the purposes of teaching the nonexpert judges how to score the occurrences of each speech symptom across the different types of voice disorders. 2.5. Perceptual rating protocol The perceptual speech symptom identification required raters to score the number of occurrences of specified parameters (defined below) for each speech sample using the rating sheet displayed in Appendix A. Unlimited playback of each sentence recording was allowed to insure that raters had adequate opportunity to accurately tally the number of speech symptom occurrences. 2.5.1. Speech symptom scoring Each subject recording began with sustained /a/ followed by the sentence recordings. Upon completion of the sustained /a/ recording, raters were instructed to rate whether periodic oscillations in pitch and loudness indicative of tremor were perceived. If raters perceived such a fluctuation, they were instructed to determine whether it was consistently or intermittently present in the sustained vowel recording. The level of tremor severity was rated as 0 (normal), 1 (intermittent), 2 (draws attention to itself), or 3 (interferes with intelligibility). Next, raters listened to each of the sentence productions and tallied how many occurrences of the following occurred: 1. Voice breaks on vowels (VB): These were defined as voice stoppages, glottal stops, or breaks in ongoing sound and could be associated with an interval of a strained ± strangled voice quality. Voice breaks typically
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occurred on voiced speech sounds such as in the sentences, ``We mow our lawn all year,'' and ``The dog dug a new bone.'' 2. Breathy breaks (BB): These were defined as sudden breathy bursts or prolongation of voiceless consonants (s, f, th, p, t, k, or h) during connected speech. Breathy breaks typically occurred on voiceless speech sounds such as, ``he'' and ``to the'' in the sentence, ``Did he go to the right or to the left?'' on ``The puppy'' and ``tape'' in the sentence, ``The puppy bit the tape,'' and on ``comes home'' and ``feed him'' in the sentence, ``When he comes home we'll feed him.'' 3. Tremor (TRE): This was defined as a periodic modulation in the voice perceived during production of a vowel during connected speech. Tremulous vowel production was best perceived during more prolonged vowel productions such as occurred during the sentences, ``We mow our lawn all year,'' ``The dog dug a new bone,'' and ``When he comes home we'll feed him.'' 2.5.2. Predominant speech symptom scoring After all of the speech samples were scored and the total number of occurrences of each type of speech symptom was determined, both the expert judges and the nonexpert judges were instructed to select the category of voice disorder representative of the predominant speech symptom. The nonexpert judges were given the following criteria for selecting from the listed voice disorder categories identified by the expert judges: 1. Subjects with larger scores for adductor voice breaks than abductor breathy breaks and fewer occurrences of vocal tremor were assigned to the category of ADSD. 2. Subjects with larger scores of abductor breathy breaks than adductor voice breaks and fewer occurrences of vocal tremor were assigned to the voice disorder category of ABSD. 3. Subjects scoring a larger total of occurrences of vocal tremor were to be assigned to one of the types of vocal tremor listed. AD tremor was defined as the presence of vocal tremor with a voice quality that was perceived as pressed, or tense. AB tremor was defined as the presence of vocal tremor with a voice quality that was perceived as breathy. 4. MTD was selected when the subject had a consistent voice quality abnormality and few voice breaks, breathy breaks, or occurrences of vocal tremor. 5. WNL represented a speech sample that was judged to be within normal limits on all voice symptom parameters. 6. Subjects judged to have large numbers of both voice breaks and occurrences of vocal tremor were assigned to ADSD + Tremor. 7. Similarly, ABSD + Tremor was assigned to subjects with large numbers of both breathy breaks and of vocal tremor.
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The final selection of the voice disorder category was used to determine whether nonexpert judges correctly determined the predominant speech symptom present in a given subject speech sample. 2.6. Nonexpert listening sessions The nonexpert listening sessions took place on two occasions separated by no more than 1 week. The first listening session consisted of the training task (approximately 1 h) followed by 1 1/2 h of the experimental rating task. The second session began with a review of the training tape anchor samples and continuation of the experimental rating task (approximately 2 1/2 h). The training task taught the nonexpert judges how to use the speech symptom parameter portions of the rating sheet. In addition, one recording of sustained /a/ and one set of five sentences for each of the five types (VB, BB, Tremor, MTD, and WNL) were presented to judges for practice using the perceptual assessment protocol. Judges participated in groups of 2 ±3 individuals seated within 3 ± 4 ft of two Optimus speakers in a quiet room. Judgements were based on acoustic recordings played at comfortable loudness as determined by the participating judges. 2.7. Data analysis The total number of instances of VB, BB, TRE, and vocal tremor for each subject was recorded by each judge for comparison. The ``correct'' number of occurrences of each speech symptom was defined as the mean total score obtained for each speech symptom type scored by the expert judges for each subject. Using the mean of the expert judge scores for each subject, the percent of exact agreement, the percentage within one point, and the percentage within two points of exact agreement were determined for the nonexpert judge scores. Repeated within subject ANOVAS were computed to test whether there were significant differences between the expert vs. the nonexpert judges in the mean numbers of voice breaks, breathy breaks, and vocal tremors identified. Because three comparisons were computed, a Bonferroni correction was used for the criterion alpha level ( P =.05/3=.016). The percent of exact agreement for the voice disorder category selected for each subject by the nonexpert judges was compared to that from the expert Table 1 Proportions (%) of agreement for expert judge scores with the average expert judge scores Type of agreement
Voice breaks
Breathy breaks
Occurrences of tremor
Exact Within 1 point Within 2 points
82 88 98
90 98 98
83 87 97
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Table 2 Proportions (%) of agreement for nonexpert judge scores with the average expert judge scores Type of agreement
Voice breaks
Breathy breaks
Occurrences of tremor
Exact Within 1 point Within 2 points
54 66 78
73 80 86
54 65 74
judges. This determined the accuracy of the nonexpert judges in identifying the predominant symptom types for each subject. To determine the ability of each of the individual nonexpert judges to identify each symptom type, listwise Pearson correlation coefficients were computed between the mean of the expert judge symptom counts and each nonexpert judge's symptom counts for each of the three symptom types. 3. Results The expert judges demonstrated high reliability with subject speech symptom scores within one point of exact agreement on 91% and exact agreement on 85% of the subject speech stimuli (Table 1). For selection of the predominant speech symptom associated with each voice disorder category, expert judges were in 100% exact agreement. One of the subjects selected by the primary investigator as having a predominant speech symptom consistent with ADSD was rated as MTD by all of the expert judges. This subject was, therefore, recategorized as having a predominant symptom type consistent with MTD. The agreement between averaged expert judge and nonexpert judge scores for each type of speech symptom is shown in Table 2. As can be seen by these data, the exact agreement for the same number of occurrences of each speech symptom
Fig. 1. Mean numbers of symptoms counted by the expert (shaded squares) and nonexpert judges (filled black circles) for each of the 20 subjects for vowel breaks (on the far left), breathy breaks (in the center), and tremor breaks (on the far right).
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Table 3 Comparison of nonexpert to expert judge scores for the predominant symptom type across subjects Nonexpert frequencies for each predominant symptom type Predominant symptom type
Expert counts
ADSD
ABSD
Vocal tremor
MTD
WNL
Nonexpert counts
ADSD ABSD Vocal tremor MTD WNL
9 12 12 16 12
14 2 1 3 0
1 16 1 0 0
0 1 17 2 1
0 1 1 20 0
0 0 0 0 19
15 20 20 25 20
There was 100% expert judge agreement for each category with a maximum N of 12 possible, except for the ADSD and MTD categories. The maximum N for each category for the nonexpert judges is 20, except for the ADSD and MTD categories. One of the subjects selected by the primary investigator as having the predominant symptom of ADSD was scored as MTD by the experts.
between judge groups was high. The proportion of agreement between and within the two groups was highest on breathy breaks for both sets of judges. The agreement between the counts for each of the subjects by the two groups of judges for each of the symptom types is shown in Fig. 1. To determine whether the designated categories that expert and nonexpert judges identified for each subject were the same, Table 3 shows the distribution of nonexpert and expert judges' categories for the predominant voice disorder category. As seen in this table, the nonexpert judges were in agreement with expert judges on 86 of the 95 classifications. Thus, the nonexpert judges learned to determine the predominant symptom type present in each subject similar to that identified by the expert judges. The mean numbers of speech symptoms of each type were compared between the two groups of judges on repeated ANOVAs within subjects between the mean scores for the two sets of judges. No significant difference ( P .016) in the number of breathy breaks or vocal tremors were found between judge groups. However, there was a significant difference between expert and nonexpert judge Table 4 Average speech symptom parameter frequencies obtained from nonexpert (NE) and expert (E) judge scores Voice breaks
Breathy breaks
Predominant speech symptom
E
NE
E
NE
Tremor MTD ADSD ABSD WNL Total
0.8 (1.1) 0.6 (0.8) 7.2 (1.9) 0 (0) 0 (0) 1.3 (2.7)
3.1 (4.2) 0.5 (0.8) 10.8 (5.9) 0.3 (1.2) 0 (0) 3.0 (5.2)
0.2 (0.4) 0 (0) 0 (0) 7.6 (2.1) 0 (0) 1.6 (3.2)
1.0 0.1 0.2 10.1 0.1 2.1
The standard deviation is displayed in parentheses.
Vocal tremor (1.7) (0.5) (0.9) (4.5) (0.2) (4.3)
E
NE
7.8 (3.4) 0.9 (1.8) 2.1 (1.6) 0.1 (0.3) 0 (0) 2.1 (3.5)
7.8 0.8 1.3 1.9 0.1 2.4
(4.0) (2.0) (2.4) (3.0) (0.5) (3.8)
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Table 5 Pearson correlation coefficients for each of the nonexpert judges in agreement with the expert judges mean scores for each break type Pearson r Judge
Vowel breaks
Breathy breaks
Tremor breaks
1 2 3 4 5
.909 .838 .587 .923 .819
.850 .967 .684 .873 .949
.813 .624 .954 .836 .754
scores on the number of voice breaks across subjects ( F = 7.68; P = .012) with the nonexpert judges counting more vowel breaks than the expert judges (Table 4). To examine the ability of each of the five nonexpert judges to agree with the expert judges, Pearson correlation coefficients were computed for each of the judges for vowel breaks, breathy breaks, and tremor (Table 5). Different judges were accurate on different symptom types, Judge 3 had poor agreement with the expert judges on vowel breaks and breathy breaks but had good agreement on tremor. Judge 2 had poor agreement with the expert judges on tremor breaks. 4. Discussion The results of this study demonstrated that nonexpert judges learned to identify predominant speech symptoms reflective of the voice disorder categories of ABSD, ADSD, and vocal tremor as compared to expert judges. While 86% exact agreement is an adequate level of agreement, a preferred outcome of such training is 100% agreement between nonexpert and expert judges. Less than 100% agreement with expert judges could relate to possible confusion identifying each of the speech symptoms. For example, nonexpert judges demonstrated 54% exact agreement with expert judges on scoring voice breaks and occurrences of vocal tremor across subjects. Correct identification of these speech symptoms is necessary for correct identification of the predominant symptom type. As indicated in Table 4, nonexpert judges more frequently scored subjects as exhibiting voice breaks than did the experts. In addition, the predominant speech symptom type was incorrectly chosen in 14 cases by the nonexpert judges. There did not appear to be a consistent error across the various predominant speech symptom types chosen erroneously by nonexpert judges. Nor was there any particular nonexpert judge who demonstrated a consistent error in selecting the predominant speech symptom type. Thus, uncertainty in choosing the predominant speech symptom type varied across subjects and nonexpert judges. Some non-expert judges, however, may not have learned to accurately identify voice symptoms. This was particularly the case for nonexpert Judge 3 for voice breaks and Judge 2 for tremor breaks.
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One hour of training was completed with nonexpert judges prior to participating in the experimental phase of the study. During this 1-h training session, only one example of each voice disorder category was presented. The training session is vital for providing instruction and practice time to nonexpert judges. Without adequate training time, nonexpert judges may not learn to accurately identify each type of speech symptom associated with ADSD, ABSD, vocal tremor, or MTD. Future work in this area may require more than 1 h for training nonexpert judges. Informally, nonexpert judges frequently commented that the training tape did not adequately prepare them for the variety of speech symptom presentations across the experimental subjects. Thus, future training sessions need to offer a wider variety of examples for each type of voice disorder and allow nonexperts more opportunities to practice identification for each type of speech symptom. Another possible factor for consideration relates to the typical clinical evaluation of individuals with ADSD, ABSD, and vocal tremor. The perceptual speech symptom identification protocol focused the attention of raters on particular speech symptom parameters in the absence of further information about each subject. Clinically, information related to patient history, conversational speech patterns, and laryngeal imaging could influence scores obtained using the current speech symptom identification protocol. While expert judges did not have access to such information for their rating sessions, nonexperts may benefit from the addition of such information. The addition of client history and laryngeal images might be expected to facilitate improved scores. An argument could also be made, however, that such additional information may interfere with judges being able to focus on speech symptoms. In addition, the literature indicates that the best method for accurately determining whether an individual exhibits ADSD or ABSD is through correct identification of the predominant speech symptom type as addressed in this study (Leonard & Kendall, 1999; Ludlow & Connor, 1987). Thus, the contribution of client history and laryngeal images to correct identification of the predominant speech symptom may be negligible. The current perceptual speech symptom identification protocol utilized a combination of speech tasks that was previously determined to best elucidate perceived speech symptoms for ADSD, ABSD, and vocal tremor. That is, sustained phonation of a vowel is the best method for determining the presence of a vocal tremor. Speech samples loaded with glottal stops and voiceless consonants help differentiate between ADSD and ABSD. The current method for scoring the number of occurrences of each type of speech symptom is different from previous methods using traditional rating scales of voice quality. For example, traditional rating scales such as the GRBAS address general voice quality and do not offer a means for scoring specific speech symptoms such as voice breaks, breathy breaks, or vocal tremor. The current method is specifically designed to assist in correctly identifying speech symptoms typical of individuals with ADSD, ABSD, and vocal tremor. The speech samples and organization of the perceptual speech symptom identification protocol would require clinicians to utilize a standard speech protocol for assessment of ADSD, ABSD, and vocal tremor. The use of this
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protocol may help nonexpert judges learn how to more accurately identify the speech symptoms most prominent in the voice disorder populations of interest. All of the nonexpert judges in this study informally commented that they learned how to appropriately test individuals with ADSD, ABSD, and vocal tremor. Perhaps over repeated application of this perceptual assessment protocol, the current nonexpert judges will improve their speech symptom identification scores. Additional investigation of nonexpert judge performance over repeated application could address questions regarding the average learning curve before nonexpert judges perform equally to expert judges. Based on the individual differences in nonexpert judge agreement with the expert judges, it could be argued that some persons require more training time than others and that training should allow for such individual training needs. Overall, the current comparison between nonexpert and expert judges using the perceptual speech symptom identification protocol indicates that this instrument may be useful for training voice clinicians to successfully identify speech symptoms characteristic of ABSD, ADSD, and vocal tremor. Additional investigation needs to be completed to determine the contribution of repeated use of this training protocol for improving speech symptom identification performance.
Acknowledgments We would like to acknowledge Kimberly Bidus and Laura Purcell for their assistance with the development of the rating sheet used as well as their part in conducting the expert judge rating sessions. Shrita Squire's contribution to dubbing the rating tapes is gratefully acknowledged. Appendix A. Subject #:_____________ Rater:_____________ Tremor rating scale: 0 = normal 1 = mild (or intermittent) 2 = moderate (draws attention to itself) 3 = severe (interferes with speech intelligibility) Tremor: Continuous:_______Overall rating:_______________ Intermittent:______ Vowel breaks Breathy breaks Tremor: The puppy bit the tape. _______ _______ _______
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We mow our lawn all year. The dog dug a new bone. Did he go to the right or to the left? When he comes home we'll feed him. Total:
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Predominant symptom type: (circle one) ADSD ABSD AD tremor AB tremor ADSD/ABSD + Tremor Other ADSD/ABSD plus Other WNL Appendix B. Continuing education Identification of symptoms for spasmodic dysphonia and vocal tremor: a comparison of expert and nonexpert judges Questions 1. The predominant speech symptom for adductor-type spasmodic dysphonia is: (a) vocal tremor (b) intermittent breathy breaks (c) consistently pressed voice quality (d) intermittent voice stoppages (e) high-pitched voice 2. The predominant speech symptom for abductor-type spasmodic dysphonia is: (a) vocal tremor (b) intermittent breathy breaks (c) consistently pressed voice quality (d) intermittent voice stoppages (e) high-pitched voice
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3. The best speech task for determining whether a vocal tremor is present is: (a) sustained phonation of a vowel (b) repetition of sentences containing primarily voiced speech sounds (c) repetition of sentences containing primarily voiceless speech sounds (d) spontaneous conversation (e) counting from one to twenty 4. The perceptual training protocol utilized in this study: (a) required raters to score the number of occurrences of each type of speech symptom rather than the traditional method of rating voice quality (b) did not combine perceptual ratings of speech recordings with information obtained from patient history information and laryngeal imaging (c) required raters to determine the presence and consistency of a vocal tremor during sustained phonation of a vowel (d) utilized both sustained phonation of a vowel and connected speech samples to score the number of occurrences of each speech symptom (e) all of the above 5. Compared to expert judges, this study demonstrated that nonexpert judges: (a) were in agreement with expert judges on 86 of the 95 predominant voice disorder category (b) demonstrated significantly different average scores across all speech symptom types compared to expert judges (c) demonstrated 100% agreement with expert judges on all of the predominant speech symptom types (d) scored lowest agreement with expert judges on breathy break scores (e) scored similar occurrences of voice breaks to expert judges
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