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Development and Evidence of Content Validity of the Spectrographic Vocal Assessment Protocol (SVAP)
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Development and Evidence of Content Validity of the Spectrographic Vocal Assessment Protocol (SVAP) Gabriele Rodrigues Bastilha, Karina Carlesso Pagliarin, and Carla Aparecida Cielo, Santa Maria, Brazil Summary: Objective. To develop and seek evidence of content validity of a spectrographic vocal assessment protocol. Methods. Methodological study for development and validation of an assessment instrument. A broad literature search was conducted to develop and substantiate a spectrographic vocal assessment protocol. The protocol items were sent to five expert judges, speech therapists, nonauthors of the research, doctors, and clinicians, with experience in the field of voice and spectrographic acoustic analysis, who individually analyzed the protocol items. For data analysis, the Gwet analysis and the Content Validity Ratio formula were used. Results. The Spectrographic Vocal Assessment Protocol was developed, subdivided into Broadband and Narrowband. Twenty-four protocol items had Content Validity Ratio 1.0 and 25 items had 0.6. Gwet analysis indicated substantial agreement (0.656) for broadband and almost perfect (0.848) for narrowband items. Conclusion. Evidence of satisfactory content validity was obtained in the development of the protocol. Key Words: Acoustics−Spectrography−Validation Studies−Speech, Language and Hearing Sciences−Voice.
INTRODUCTION Vocal assessment should analyze all dimensions of vocal behavior, so it is recommended to conduct a multidimensional voice assessment, considered the basis of diagnostic and therapeutic clinical reasoning.1−10 Among the existing assessments in the vocal clinic, there are auditory perceptual, self-assessment, aerodynamic measurements, glottal source acoustics, spectrographic acoustics, and visual perceptual analysis of laryngoscopy.3−6,8−9,11−13 The visual recording of sound wave analysis through vocal spectrography presents the distribution of energy in relation to frequency and time, allowing the visualization of noise recording, among other aspects. Spectral components belonging to vocal alterations may be related to different vocal qualities and characteristics of acoustic energy distribution.6,10−12,14−18 This analysis provides data that is related to the vibratory pattern of the vocal folds, the shape of the vocal tract and its changes in time, and these data vary with age, gender, vocal training, and phonation type.5,11,17,19,20 Spectrographic acoustic analysis is therefore an important part of multidimensional vocal assessment. It can be used in both research and clinical practice to characterize vocal disorders and voices of different populations, to assess patient outcome and the effect of speech therapy, and as a visual feedback of the emission.5,6,11,14−16,21,22 However it depends on the evaluator's visual analysis, which characterizes an aspect of subjectivity in this analysis. Therefore, the importance of developing and validating a spectrographic vocal assessment protocol (SVAP) was Accepted for publication December 6, 2019. From the Department of Speech-Language Pathology and Audiology, Universidade Federal de Santa Maria/UFSM, Santa Maria, Rio Grande do Sul, Brazil. Address correspondence and reprint requests to Gabriele Rodrigues Bastilha, Department of Speech-Language Pathology and Audiology, Universidade Federal de Santa Maria/UFSM, Av. Roraima no 1000, Prédio 26, 97105-900 Santa Maria, Brazil. E-mail: [email protected] Journal of Voice, Vol. &&, No. &&, pp. &&−&& 0892-1997 © 2019 The Voice Foundation. Published by Elsevier Inc. All rights reserved. https://doi.org/10.1016/j.jvoice.2019.12.008
realized, covering aspects that are fundamental in this type of analysis, based on the studies found in the literature. These studies bring different approaches to the assessment of spectrographic images,1,6,8,12,18,23−27 which makes the spectrographic vocal assessment even more subjective and hinders the analyses and, consequently, the standardization of results and their understanding by the clinical speech therapist. Thus, the validation of a protocol for spectrographic vocal assessment could provide standardization of assessments, interpretation of their results, and help speech therapists in both clinical practice and scientific research. Assessments based on specific protocols allow the clinician to act in a planned manner, to document procedures, solidifying and sustaining with scientific evidence the clinical practices. Validation of the protocol could also facilitate peer discussion of the analyzed spectrographic vocal aspects.11,16,28 Regarding the protocol development and validation process, there are a number of methodological criteria that must be strictly followed. The elaboration process must be carefully planned so that the instrument can be able to assess and provide data relevant to what it proposes to investigate.28−30 In this sense, evidence of validity allows for more accurate decision making and increases scientific rigor in interpreting instruments.28,31 One of the types of validity, content validity requires the test to present a representative sample of a finite universe of behaviors. To enable a content-validated test, test specifications must be made prior to constructing the items.31,32 Content validity is verified from the analysis of individuals with expertise in the area about the semantic understanding of the items that make up the instrument (clarity) and the relevance/pertinence of these items.12,31 To standardize the aspects that are important in spectrographic analysis and considering the lack of validated instruments in this area, this study aimed to develop and seek evidence of content validity of a SVAP.
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METHODS Study design This is a methodological research, approved by the Ethics Committee on Research with Human Beings of the home institution with the number 1.570.886. Participants To select the volunteers participating in this research, a search was made through the Lattes CNPq database of Voice specialists from different regions of Brazil. Aspects such as formation, production (articles and abstracts), and projects with the subject spectrographic acoustic analysis were considered. Initially, eight judges were selected, but three were excluded because they had no experience with spectrographic analysis specifically, only with acoustic analysis. Finally, the judges selected were five speech therapists, nonauthors of the research (doctors and clinicians), with experience in the field of voice and spectrographic vocal analysis of at least five years, who independently analyzed the items of the proposed protocol.12,32,33 The judges were invited to participate by e-mail and signed an informed consent form. Procedures This research aims to present the development and content validation process of an assessment instrument. This process is subdivided into the development of the instrument, with extensive literature review for the theoretical foundation of the aspects to be assessed by the instrument, and content validation.31 Therefore, the methodological procedures performed were described from this subdivision. Protocol development The SVAP was constructed based on the literature, considering the aspects analyzed in spectrographic vocal assessments and encompassing the largest possible number of parameters.1,6,13,15,16,18,22−26,34−37 SVAP has been used by our research group since the late 1990s. Several spectrographic vocal aspects not validated in the literature and currently used in clinical and speech therapy research were identified and included in a single protocol. Thus, the SVAP was elaborated, consisting of two parts: Broadband Spectrography (BS) and Narrowband Spectrography (NS). Each part with its respective aspects/parameters to be assessed, as well as general written instructions to the evaluators for ease of understanding. To fill the SVAP, a linear analog scale with a score ranging from 0 to 10 cm is used. The assessment of each parameter should be performed by marking a vertical line at any point on the millimeter ruler, according to the observed gradation.2,4,6,8,22,37 In BS, the following parameters are assessed: formant tracing color intensity (1st Formant-F1, 2nd Formant-F2, 3rd Formant-F3, and 4th Formant-F4), of low, medium, and high frequencies and the whole spectrography vocal; tracing regularity at whole vocal spectrogram and at low, medium, and high frequencies; definition, regularity, and bandwidth of
F1, F2, F3, and F4; and antiresonance/damping immediately above F1, at whole vocal spectrography and at low, medium, and high frequencies. In the NS analysis, the following are assessed: tracing color intensity, definition, regularity, and number of harmonics, presence of subharmonics, presence of noise and replacement of harmonics by noise at low, medium, and high frequencies and at whole vocal spectrography.6,8,12,13,15,16,22−26,34,36−39 For purposes of parameter analysis, low frequencies below 1500 Hz, medium frequencies between 1500 and 3000 Hz and high frequencies above 3000 Hz are considered.5,23,25,35,40 The first part of the protocol consists of five items, with their respective subitems, related to BS, detailed below: 1. Tracing color intensity of the four F, low, medium, and high frequencies, and in vocal spectrography as a whole: The tracing color intensity is related to the acoustic signal sound pressure. In spectrography, the degree of darkening present in the trace should be considered, which may vary from black (corresponding to 10 cm), indicating strong signal sound pressure, to light gray, indicating weak sound pressure, or white, suggesting silence. Reduction in the tracing color intensity of some F may suggest nasality, such as F1 or F3, being considered as a result of the addition of damping characteristics on the nasal cavity wall surfaces. Tracing color intensity should be analyzed at each of the four Fs, as well as at low, medium, and high frequencies and in vocal spectrography as a whole.5,26,27,41−43 2. Definition and regularity of the four Fs: The visible, well-demarcated and symmetrical Fs along their temporal representation are considered to be well-defined and regular (corresponding to 10 cm). F that are poorly visible, poorly demarcated, and/or asymmetrical may be considered with an altered definition and F unidentifiable are considered absent with 0 cm marking.22,27,35 3. Tracing regularity at low, medium, and high frequencies and in spectrography as a whole: This aspect deals with the continuity and stability of the vertical striation tracing and relates to the presence of noise or aperiodicity in the sound signal. Thus, a continuous and regular tracing corresponds to 10 cm (total tracing regularity) and a tracing dominated by oscillations, erasures or other types of irregularities corresponds to the total irregularity (0 cm).25,27 4. Bandwidth of the four Fs: The Fs are classified according to their bandwidth, with 10 cm being fully increased and 0 cm being fully decreased F band. F bandwidth represents the effective frequency range of resonator response and increased bandwidth may suggest hypernasality.13,27,44 The increase in F113 and F344 bandwidth is related to the auditory-perceptive characteristic of breathiness. 5. Anti-resonance/damping immediately above F1, at low, medium, and high frequencies and in spectrography as a whole: Described in the literature as an acoustic muffling due to sound dampening, this aspect may be
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related to the direction of sound to the nasal cavity. It corresponds to 10 cm in the domain of erasure spectrography (blank or much lighter than the rest of the spectrography) and 0 cm no identified erasure.27,41,43 The second part of the protocol consists of six items and their respective subitems related to NS: 1. Tracing color intensity of low, medium, and high frequency and in vocal spectrography as a whole: As already mentioned, tracing color intensity refers to sound pressure. The degree of darkening should be considered, which may vary from black (corresponding to 10 cm), indicating strong signal sound pressure, to light gray, indicating weak sound pressure, or white, indicating silence.12,16,26,27 2. Presence of noise at low, medium and high frequencies and in vocal spectrography as a whole: Noise appears in spectrography as a shaded or dotted image and is associated with the aperiodicity of the sound signal. Shading may vary in color intensity from black (corresponding to 10 cm), indicating more noise, to light gray indicating less noise or white, indicating no noise.5,16,26,27,37,40 3. Replacement of harmonics by noise at low, medium, and high frequencies and in vocal spectrography as a whole: Noisy voices can have their harmonics replaced by noise at NS and this can happen especially at high frequencies, showing a voice poor in vocal projection. The absence of harmonics above 3000 Hz in altered voices occurs because aperiodic sound waves are not uniformly amplified, which prevents their multiples from being represented as harmonics in the graph. Thus, the region above 3000 Hz may appear darkened only by the presence of noise.12,40 10 cm for total replacement of harmonic by noise is considered. 4. Definition and regularity of harmonics at low, medium, and high frequencies and in vocal spectrography as a whole: In a normal voice, harmonics (horizontal lines) are expected to be well defined and continuous, showing adequate glottal closure, absence of air escape to phonation, adequate sound pressure, and periodicity in mucosal vibration, showing a regular and well defined tracing (corresponding to 10 cm). When this does not occur, there is a tracing with undefined harmonics, with cuts and or irregularities.16,26,27,35,36,40 5. Number of harmonics at low, medium, and high frequencies and in vocal spectrography as a whole: This relates to the quantity of harmonics present in spectrography in the analyzed frequency range. The 10 cm marking is considered for the complete filling of the spectrographic image by harmonics and 0 cm for the complete absence of harmonics in the NS.26,37 6. Presence of subharmonics in low, medium, and high frequencies and in vocal spectrography as a whole: This is a tracing present between two consecutive harmonics, showing a source of vibration beyond the vocal folds or signifying the presence of noise in the sign. They can be
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a partial or total duplication of harmonics. In this item, 10 cm corresponds to the presence of subharmonics at a whole spectrography and 0 cm to the complete absence of subharmonics in the NS image.16,23,26,34−37 Content validation The five judges received the SVAP by email and were instructed to carefully analyze their items, classified each item of the instrument as "essential" or "not necessary," in others words, if these were needed to be included or not. Each item of the instrument presented a brief orientation (Appendix A) and the judges relating their inclusion with concepts and theoretical considerations. Data analysis was performed by calculating the Content Validity Ratio (CVR) for each item. CVR was obtained by the formula CV = (ne N/2)/(N/2), where he is the number of judges who considered the item as adequate and N represents the total number of judges. Also, to verify agreement among judges, Gwet's first-order agreement coefficient (AC1) statistical calculation was used.45 AC1 agreement was measured by Landis and Koch criteria46 where >0.8 is considered almost perfect, 0.61−0.8 is substantial, 0.41−0.6 is moderate, 0.21−0.4 is regular, and <0.2 is bad. RESULTS The analysis of the SVAP items is shown in Tables 1 and 2 (BS and NS, respectively), with the values of CRV and AC1 Gwet analysis. As for CVR, 24 protocol items had CVR = 1.0 and 25 items had CVR = 0.6. In the AC1 Gwet analysis for SVAP broadband items, agreement was considered substantial and for narrowband items it was almost perfect. The SVAP in its final version was a total of 49 items, subdivided into BS (25 items) and NS (24 items), accompanied by the 10 cm scale for marking items and an initial part with general instructions for filling the protocol (Appendix A). DISCUSSION This study aimed to develop and seek evidence of SVAP content validity, analyzing whether the items that compose it are really clear and relevant, contributing to the standardization of visual analysis and reduction of subjectivity in vocal spectrographic assessment. The results of the Gwet analysis indicated agreement among experts considered substantial for BS (Table 1) and almost perfect for NS (Table 2), reinforcing the evidence of SVAP content validity. In the CVR results (Tables 1 and 2), when only one of the judges did not agree with the protocol item, the index was 0.6, denoting moderate CVR. Therefore, after discussions among the authors and based on the literature, these items were kept. It is noteworthy that for the development of SVAP, the largest possible number of spectrographic vocal aspects were identified and gathered in the available literature and used in clinical and speech therapy research.1,6,13,15,16,18,22−26,34−37 It
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TABLE 1. Analysis of Spectrographic Vocal Assessment Protocol (Broadband Spectrography) Items SVAP Item − Broadband Tracing color intensity of F1 Tracing color intensity of F2 Tracing color intensity of F3 Tracing color intensity of F4 Tracing color intensity of low frequencies Tracing color intensity of medium frequencies Tracing color intensity of high frequencies Tracing color intensity in vocal spectrogram as a whole Definition and regularity of F1 Definition and regularity of F2 Definition and regularity of F3 Definition and regularity of F4 Regularity of vertical striation tracing at low frequencies Regularity of vertical striation tracing at medium frequencies Regularity of vertical striation tracing at high frequencies Regularity of vertical striation tracing in vocal spectrogram as a whole Bandwidth of F1 Bandwidth of F2 Bandwidth of F3 Bandwidth of F4 Anti-resonance/damping immediately above F1 Anti-resonance/damping at low frequencies Anti-resonance/damping at medium frequencies Anti-resonance/damping at high frequencies Anti-resonance/damping in vocal spectrogram as a whole
CVR
AC1
1.0 1.0 1.0 0.6 0.6 0.6 0.6 0.6 1.0 1.0 1.0 0.6 1.0 1.0 1.0 0.6 0.6 0.6 0.6 0.6 0.6 0.6 0.6 0.6 0.6
0.656 [CI = 0.509−0.804]
Gwet’s AC1 Coefficient. Abbreviations: SVAP, spectrographic vocal assessment protocol; CVR, content validity ratio; AC1,Gwet’s AC1 coefficient; F1, 1st formant; F2, 2nd formant; F3, 3rd formant-F3; F4, 4th formant; CI, confidence interval.
is also worth mentioning that the SVAP has been used by our research group since the late 1990s. The elaboration and validation of a protocol to guide the spectrographic vocal assessment by speech therapists is of fundamental importance, aiming to guarantee the quality and standardization of the instruments. Parameters for expanding the possibility of discussion with the literature and greater possibility of scientific advancement in this area.11,28 A recent study has found that visual support of spectrographic imaging significantly increases the reliability of auditory-perceptive voice assessment, as it promote increased inter and intraevaluator agreement.11 This reinforces vocal spectrography as a complementary instrument to other vocal and laryngeal assessments, but it is considered a subjective assessment. It was observed through the literature review that there is a shortage of spectrographic assessment protocols used in research, mainly validated. Only one study found evidence of the content of a narrowband spectrographic vocal analysis protocol. In this study, The Content Validity Index was used to investigate the level of agreement among judges on the overall aspect, items, and domains of the protocol. The proposed protocol was considered comprehensive and the items presented good to excellent content validity for clarity and relevance. After this validation step, the protocol now
has 25 items, all referring only to NS, distributed among the five domains (beginning of emission, temporal aspects of emission, energy distribution in the tracing, harmonic description, and noise distribution in the tracing).12 It is noteworthy that the items of this protocol are also included in the SVAP, plus those of NS and BS considered relevant through the literature review.1,6,13,15,16,18,22−26,34−38,43,44 Another study elaborated the Visual/Spectrographic Analysis Protocol, but it was not validated. The evaluator should classify the following NS parameters: spectrographic tracing shape (regular, irregular, or absent), degree of harmonic darkening (strong, normal, weak, or unobservable), spectrographic tracing stability (stability, instability, or cannot be assessed), presence of noise (present or absent), presence of subharmonics (present or absent), definition of harmonics (the evaluator should write to what frequency the harmonics were defined.26 All these items are present in SVAP. The same protocol mentioned earlier26 was used in another study to assess the effect of visual training on spectrographic analysis. Four hours of training for the judges were performed with the analysis of 100 spectrographs. Regarding intrasubject agreement, the aspects of tracing darkening, tracing stability, presence of sub-harmonics, and definition of harmonics improved and the other aspects maintained almost perfect agreement after training. Regarding
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TABLE 2. Analysis of Spectrographic Vocal Assessment Protocol (Narrowband Spectrography) Items SVAP Item − Narrowband Tracing color intensity of low frequencies Tracing color intensity of medium frequencies Tracing color intensity of high frequencies Tracing color intensity in vocal spectrogram as a whole Presence of noise at low frequencies Presence of noise at medium frequencies Presence of noise at high frequencies Presence of noise in vocal spectrogram as a whole Replacement of harmonics by noise at low frequencies Replacement of harmonics by noise at medium frequencies Replacement of harmonics by noise at high frequencies Replacement of harmonics by noise in vocal spectrogram as a whole Definition and regularity of harmonics at low frequencies Definition and regularity of harmonics at medium frequencies Definition and regularity of harmonics at high frequencies Definition and regularity of harmonics in vocal spectrogram as a whole Number of harmonics at low frequencies Number of harmonics at medium frequencies Number of harmonics at high frequencies Number of harmonics in vocal spectrogram as a whole Presence of subharmonics at low frequencies Presence of subharmonics at medium frequencies Presence of subharmonics at high frequencies Presence of subharmonics in vocal spectrogram as a whole
CVR
AC1
1.0 1.0 1.0 0.6 1.0 1.0 1.0 0.6 1.0 1.0 1.0 0.6 1.0 1.0 1.0 0.6 0.6 1.0 0.6 0.6 0.6 1.0 1.0 0.6
0.848 [CI = 0.742−0.953]
Gwet’s AC1 Coefficient. Abbreviations: SVAP, spectrographic vocal assessment protocol; CVR, content validity ratio; AC1, Gwet’s AC1 coefficient; CI, confidence interval.
intersubject agreement, the aspects of tracing stability and the presence of subharmonics improved, and the noise presence aspect worsened after training.16 According to the literature, the parameters of BS generally assessed are: F intensity;8,10,27,47 tracing color intensity;8,10,27,47 presence of noise;8,10,27,47 F bandwidth;13,27,44 definition of F;8,10,27,47 tracing regularity,8,10,27,47 and antiresonance/ damping.27,41 In the studies with NS, the following aspects were analyzed: tracing color intensity;2,8,10,12,16,22,26,27,37,47 presence of noise between harmonics;4,8,10,12,16,22,26,27,37,47 replacement of harmonics by noise;8,10,12,47 definition of harmonics;2,8,10,12,16,26,27,47 tracing regularity;4,8,10,12,16,22, 26,27,37,47 number of harmonics,2,4,8,10,12,16,22,26,37,47 and presence of subharmonics.2,4,8,10,16,22,26,37,47 The literature reports that the lower F, F1, and F2, are related to the height and anteriority of the tongue within the oral cavity, determining the quality and identity of the vowels. The upper F F3, F4, and F5 are related to vocal quality. This is because the frequencies of the lower F are related to the tongue configuration in the vocal tract and the upper F to the vocal tract length and dimension in and around the larynx. The upper F is more evident in the voices of singers and actors, because their voices have higher quality and projection. Therefore, voices of normal speakers, who do not have vocal training, do not usually have good definition of upper F, and F4 and F5 may not be observable.10,27
The bandwidth of F represents the effective frequency range of resonator response, that is, the frequency range around which a resonator will respond to a stimulus.44 Increased bandwidth may suggest hypernasality.27,44 Still, a recent study related the increase in F113 and F344 bandwidth with the perceptual characteristic of breathiness. The phenomenon called “antiresonance or damping” is described in the literature as an acoustic dampening due to sound deadening. This aspect may be related to the direction of sound to the nasal cavity, where the tissues are softer, causing energy loss mainly in the higher harmonics. The phenomenon is also known in the literature as “damping, drop in intensity, or negative resonance in high frequencies.”27,41,43 In a group of young adult men with unaffected larynx and no vocal complaints, antiresonance/damping was considered median, that is, between very and little present, when judged by three speech therapists with voice experience.27 A study with patients undergoing septoplasty hypothesized that after surgery there would be a decrease in antiresonance/damping and an increase in voice amplitude or energy, but there was no statistical difference between preand postoperative moments.43 High frequency erasures besides suggesting nasality also indicate breathiness and low loudness.27,43,44 The contraction of the laryngeal adductor musculature increases the phonatory effort at the beginning of emission, the resistance to air flow and the closed phase of the glottic
ARTICLE IN PRESS 6 cycle. This generates increased tracing energy at high frequencies due to increased sound pressure, being common in cases of vocal fold mass injury.12 The reduction in tracing color intensity may be related to inefficient glottic closure, inefficient use of resonance cavities, and/or decreased sound pressure.12,26,27,41,42 The presence of noise on spectrography is an important indicator of the presence of vocal and/or laryngeal alterations, either throughout the emission or in specific sections.12 The replacement of harmonics by noise is related to aerodynamic, neurological, and biomechanical issues that cause signal aperiodicity. The more deviated the vocal signal, the greater the replacement of the harmonic structure by noise.12,27 The presence of well-defined regular harmonics is a characteristic of healthy voices. It indicates good glottal coaptation and greater regularity in vocal fold mucosa vibration. When spectrographic tracing appears less defined, it may suggest the beginning of vocal alteration development.8 The tracing is considered irregular when fluctuations in the behavior of energy and noise along the emission are observed, related to the fluctuation in the emission.11,12 The presence of a rich series of harmonics in spectrography indicates adequate glottal closure and vocal projection, while altered voices usually present harmonics only up to the 2000 Hz range.40 High frequency harmonics are observed more in individuals who make professional use of the voice, such as actors, singers, and teachers, and in people who have performed vocal training, indicating vocal projection and high loudness. Thus, decreasing the number of harmonics in this frequency range does not necessarily indicate vocal alteration, but may be a typical characteristic of untrained voices.12,27 The subharmonic is usually associated with the vibratory irregularity of the vocal fold mucosa, and may be related to the presence of roughness present at emission and/or more intense vocal deviation, being easily identified in spectrography. The presence of subharmonics may also show a source of vibration beyond the vocal folds.16,23,26,34−37 It is noteworthy that these were some of the studies that served as theoretical basis for the elaboration of SVAP, encompassing the largest possible number of parameters commonly used in clinical and speech therapy research, but without standardization.1,6,13,15,16,18,22−26,34−38,43,44,47 SVAP condenses and outlines important concepts of spectrographic evaluation that allow detailed and more objective analysis of the images, helping the clinician and researcher. The protocol may serve to characterize the voice of a patient or populations, as well as to track therapy outcomes and as visual feedback to patients. As a limitation of this study, there is a shortage of literature for further discussion of the results in which there is only a narrowband protocol with content validity.12 Further research should be conducted using SVAP in different populations, as well pre- and post-treatment groups can be compared using evidence of sensitivity to provide normative data for various circumstances.
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CONCLUSION SVAP presents evidence of satisfactory content validity. The final version of the protocol, after this validation step, has a total of 49 items, being 25 in BS and 24 in NS. Acknowledgements This study was financed in part by the Coordena¸c ~ ao de Aperfei¸c oamento de Pessoal de Nível Superior - Brasil (CAPES) - Finance Code 001. SUPPLEMENTARY MATERIALS Supplementary material associated with this article can be found in the online version at https://doi.org/10.1016/j. jvoice.2019.12.008. APPENDIX A SPECTROGRAPHIC VOCAL ASSESSMENT PROTOCOL Instructions: Using a linear analog scale with a score ranging from 0 to 10 cm, the evaluation of each aspect of the protocol should be carried out by marking a vertical line at any point on the ruler, according to the gradation observed at each aspect. For purposes of parameter analysis, low frequencies below 1500 Hz, medium frequencies between 1500 and 3000 Hz, and high frequencies above 3000 Hz should be considered. BROADBAND VOCAL SPECTROGRAPHY 1. Color intensity of tracing In this item, zero corresponds to the total colorlessness of the trace, and 10 corresponds to the extreme color intensity of the spectrographic trace.
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2. Definition and regularity of formants In this item, zero corresponds to the total irregularity and indefinition and 10 to the maximum regularity and definition of the formants.
3. Trace regularity In this item, zero corresponds to the total irregularity and 10 to the maximum regularity of the trace.
4. Bandwidth In this item, zero corresponds to fully reduced/absent and 10 to fully increased.
5. Anti-resonance/damping In this item, zero corresponds to the total absence of erasures (blanks or much lighter than the rest in the spectrography) and 10 to the presence/domain of the erasure spectrography window.
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NARROWBAND VOCAL SPECTROGRAPHY 1. Color intensity of tracing In this item, zero corresponds to the total colorlessness of the trace, and 10 corresponds to the extreme color intensity of the spectrographic trace.1.1 Of the low frequencies
2. Presence of noise In this item, zero corresponds to the total absence of noise and 10 to the maximum noise (shaded image) present.
3. Noise replacement of harmonics In this item, zero corresponds to the absence of noise harmonic replacement and 10 to the total noise harmonic replacement.
4. Harmonic definition and regularity In this item, zero corresponds to the total irregularity and indefinition and 10 to the total regularity and definition of the harmonics.
ARTICLE IN PRESS 8 5. Number of harmonics In this item, zero corresponds to the absence of harmonics and 10 to the complete filling of the harmonic spectrographic image.
6. Presence of subharmonics In this item, zero corresponds to the absence of subharmonics and 10 to the presence of subharmonics throughout the spectrography.
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Journal of Voice, Vol. &&, No. &&, 2019 11. Souza A, Gama ACC. Spectrographic trace visual support: impact on reliability of auditoryperceptual voice analysis by inexperienced evaluators. Disturbios Comun. 2015;27:483–490. 12. Lopes LW, Alves GAS, Melo ML. Content evidence of a spectrographic analysis protocol. Rev CEFAC. 2017;19:510–528. https://doi. org/10.1590/1982-021620171942917. 13. Narasimhan SV, VishaL K. Spectral measures of hoarseness in persons with hyperfunctional voice disorder. J Voice. 2017;31:57–61. https:// doi.org/10.1016/j.jvoice.2016.03.005. 14. Fawcus M. Disfonias - Diagnostico e Tratamento. Rio de Janeiro: Revinter; 2001:386p. 15. Zimmer V, Cielo CA, Finger LS. Spectrography acoustic vocal modifications produced by reverse phonation. Rev CEFAC. 2010;12:135– 142. https://doi.org/10.1590/S1516-18462010005000005. 16. Valentim AF, C^ ortes MG, Gama AC. Spectrographic analysis of the voice: effect of visual training on the reliability of evaluation. Rev Soc Bras Fonoaudiol. 2010;15:335–342. https://doi.org/10.1590/S151680342010000300005. 17. Hillenbrand JM. Acoustic analysis of voice: A tutorial. Perspect Speech Sci Orofac Disord. 2011;21:31–43. 18. Lima JPM. Modifica¸c ~oes Vocais e Laríngeas Imediatas em Mulheres Apos a Técnica de Fona¸c ~ao em Tubo de Vidro Imerso em Agua. 134f.. Santa Maria: Universidade Federal de Santa Maria; 2013. [Dissertation]. 19. Barros APB, Carrara de Angelis E. Análise ac ustica da voz. In: Dedivitis, Barros, eds. Métodos de Avalia¸c ~ao e Diagnostico da Laringe e Voz. S~ao Paulo: Lovise; 2002:200–221. 20. Martens J, Versnel H, Dejonckere PH. The effect of visible speech in the perceptual rating of pathological voices. Arch Otolaryngol Head Neck Surg. 2007;133:178–185. https://doi.org/10.1001/archotol.133.2.178. 21. Gama ACC, Santos LLM, Sanches NA, et al. Studying the effect of spectrogram visual support of in the auditory-perceptive voice evaluation reliability. Rev CEFAC. 2011;13(2):314–321. https://doi.org/ 10.1590/S1516-18462010005000123. 22. Falc~ao LMG, Masson MLV, Oliveira G, et al. Spectrographic analysis of the effect of vocal warm-up on the voice of choir girls. Audiol Commun Res. 2014;19:380–386. https://doi.org/10.1590/ S2317-64312014000300001372. 23. Nunez-Batalla F, Nieto SC, Pinto MC, et al. Estudio sonográfico de la disfonía: subarm onicos. Acta Otorrinolaringol Esp. 2000;51:23– 27. 24. Nemr K, AmarII A, Abrah~ao M, et al. Comparative analysis of perceptual evaluation, acoustic analysis and indirect laryngoscopy for vocal assessment of a population with vocal complaint. Rev Bras Otorrinolaringol. 2005;71:13–17. https://doi.org/10.1590/S003472992005000100003. 25. Sprecher A, Olszewski A, Jiang JJ. Updating signal typing in voice: Addition of type 4 signals. J Acoust Soc Am. 2010;127:3710–3716. https://doi.org/10.1121/1.3397477. 26. C^ ortes MG, Gama ACC. Visual analysis of spectrographic parameters before and after dysphonia therapy. Rev Soc Bras Fonoaudiol. 2010;15:243–249. https://doi.org/10.1590/S1516-80342010000200016. 27. Beber BC, Cielo CA. Features of wide and narrow band spectrography as for vocal emission of men with larynx without diseases. Rev CEFAC. 2012;14:290–297. https://doi.org/10.1590/S151618462012005000008. 28. Pernambuco L, Espelt A, Virgílio HMJ, et al. Recommendations for elaboration, transcultural adaptation and validation process of tests in Speech, Hearing and Language Pathology. CoDAS. 2017;29:5–8. https://doi.org/10.1590/2317-1782/20172016217. 29. Braga CG, Cruz DALM. Psychometric contributions to the assessment of psychosocial responses in nursing. Rev Esc Enferm. 2006;40:98–104. https://doi.org/10.1590/S0080-62342006000100014. 30. Gasparini G, Behlau M. Quality of life: validation of the Brazilian version of the Voice-Related Quality of Life (V-RQOL) Measure. J Voice. 2009;23:76–81. https://doi.org/10.1016/j.jvoice.2007.04.005. 31. Pasquali L. Psychometrics. Rev Esc Enferm. 2009;43:992–999. https:// doi.org/10.1590/S0080-62342009000500002.
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32. Hutz CS, Bandeira DR, Trentini CM. Psicometria. Porto Alegre: Artmed; 2015:192p. 33. Alexandre NMC, Coluci MZO. Content validity in the development and adaptation processes of measurement instruments. Ci^enc Saude Coletiva. 2011;16:3061–3068. https://doi.org/10.1590/S1413-81232011000800006. 34. Titze IR. Workshop on Acoustic Voice Analysis: Summary Statement. Denver: National Center for Voice and Speech; 1995:36 p. 35. Nunez-Batalla F, Santos PC, González BS, et al. Evaluaci on espectral cuantitativa de la hipofunci on vocal. Acta Otorrinolaringol Esp. 2004;55:327–333. https://doi.org/10.1016/S0001-6519(04)78531-3. 36. Nunez-Batalla F, Molina JPD, L opez IG, et al. El espectrograma de banda estrecha como ayuda para el aprendizaje del método GRABS de análisis perceptual de la disfonía. Acta Otorrinolaringol Esp. 2012;63:173–179. https://doi.org/10.1016/j.otorri.2011.10.002. 37. Medina V, Simoes-Zenari M, Nemr NK. Acoustic voice analysis: effect of an audio-visual training for speech therapy undergraduates. Audiol Commun Res. 2015;20:123–129. https://doi.org/10.1590/S231764312015000200001419. 38. Schwarz K, Cielo CA. Vocal and laryngeal modifications produced by the sonorous tongue vibration technique. Pro-Fono R Atual Cient. 2009;21:161–166. https://doi.org/10.1590/S0104-56872009000200013. 39. Rodriguez-Parra MJ, Adrian JA, Casado JC. Comparing voice-therapy and vocal-hygiene treatments in dysphonia using a limited multidimensional evaluation protocol. J Commun Disorders. 2011;44:615– 630. https://doi.org/10.1016/j.jcomdis.2011.07.003.
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40. Pontes PAL, Vieira VP, Goncalves MIR, et al. Characteristics of hoarse, rough and normal voices: acoustic spectrographic comparative analysis. Rev Bras Otorrinolaringol. 2002;68:182–188. https://doi.org/ 10.1590/S0034-72992002000200005. 41. PInho SMR, Camargo Z. Introdu¸c ~ao a análise ac ustica da voz e da fala. In: Pinho, ed. Topicos em Voz. Rio de Janeiro: Guanabara Koogan; 2001:19–44. 42. Mendon¸c a RA, Sampaio TMM, Oliveira DSF. Assessing of a vocal functional exercise program the Stemple and Gerdeman apllied to teachers. Rev CEFAC. 2009;12:471–482. https://doi.org/10.1590/ S1516-18462010005000069. 43. Ozbal-Koc EA, Koc B, Ercan I, et al. Effects of septoplasty on speech and voice. J Voice. 2014;28. https://doi.org/10.1016/j.jvoice.2013.09.008. 393.e11-5. 44. Magri A, Stamado T, Camargo ZA. Formant bandwidth influences in voice quality. Rev CEFAC. 2009;11:296–304. https://doi.org/10.1590/ S1516-18462009005000010. 45. Gwet KL. Computing inter-rater reliability and its variance in the presence of high agreement. Br J Math Stat Psychol. 2008;61:29–48. https://doi.org/10.1348/000711006X126600. 46. Landis JR, Koch GG. The measurement of observer agreement for categorical data. Biometrics. 1977;33:159–174. 47. Cielo CA, Ribeiro VVR, Bastilha GRB. Spectrographic voice measures, vocal complaints and occupational data of elementary school teachers. Disturb Comum. 2015;27:299–308.
Development and Evidence of Content Validity of the Spectrographic Vocal Assessment Protocol (SVAP) Gabriele Rodrigues Bastilha, Karina Carlesso Pagliarin, and Carla Aparecida Cielo, Santa Maria, Brazil Summary: Objective. To develop and seek evidence of content validity of a spectrographic vocal assessment protocol. Methods. Methodological study for development and validation of an assessment instrument. A broad literature search was conducted to develop and substantiate a spectrographic vocal assessment protocol. The protocol items were sent to five expert judges, speech therapists, nonauthors of the research, doctors, and clinicians, with experience in the field of voice and spectrographic acoustic analysis, who individually analyzed the protocol items. For data analysis, the Gwet analysis and the Content Validity Ratio formula were used. Results. The Spectrographic Vocal Assessment Protocol was developed, subdivided into Broadband and Narrowband. Twenty-four protocol items had Content Validity Ratio 1.0 and 25 items had 0.6. Gwet analysis indicated substantial agreement (0.656) for broadband and almost perfect (0.848) for narrowband items. Conclusion. Evidence of satisfactory content validity was obtained in the development of the protocol. Key Words: Acoustics−Spectrography−Validation Studies−Speech, Language and Hearing Sciences−Voice.
INTRODUCTION Vocal assessment should analyze all dimensions of vocal behavior, so it is recommended to conduct a multidimensional voice assessment, considered the basis of diagnostic and therapeutic clinical reasoning.1−10 Among the existing assessments in the vocal clinic, there are auditory perceptual, self-assessment, aerodynamic measurements, glottal source acoustics, spectrographic acoustics, and visual perceptual analysis of laryngoscopy.3−6,8−9,11−13 The visual recording of sound wave analysis through vocal spectrography presents the distribution of energy in relation to frequency and time, allowing the visualization of noise recording, among other aspects. Spectral components belonging to vocal alterations may be related to different vocal qualities and characteristics of acoustic energy distribution.6,10−12,14−18 This analysis provides data that is related to the vibratory pattern of the vocal folds, the shape of the vocal tract and its changes in time, and these data vary with age, gender, vocal training, and phonation type.5,11,17,19,20 Spectrographic acoustic analysis is therefore an important part of multidimensional vocal assessment. It can be used in both research and clinical practice to characterize vocal disorders and voices of different populations, to assess patient outcome and the effect of speech therapy, and as a visual feedback of the emission.5,6,11,14−16,21,22 However it depends on the evaluator's visual analysis, which characterizes an aspect of subjectivity in this analysis. Therefore, the importance of developing and validating a spectrographic vocal assessment protocol (SVAP) was Accepted for publication December 6, 2019. From the Department of Speech-Language Pathology and Audiology, Universidade Federal de Santa Maria/UFSM, Santa Maria, Rio Grande do Sul, Brazil. Address correspondence and reprint requests to Gabriele Rodrigues Bastilha, Department of Speech-Language Pathology and Audiology, Universidade Federal de Santa Maria/UFSM, Av. Roraima no 1000, Prédio 26, 97105-900 Santa Maria, Brazil. E-mail: [email protected] Journal of Voice, Vol. &&, No. &&, pp. &&−&& 0892-1997 © 2019 The Voice Foundation. Published by Elsevier Inc. All rights reserved. https://doi.org/10.1016/j.jvoice.2019.12.008
realized, covering aspects that are fundamental in this type of analysis, based on the studies found in the literature. These studies bring different approaches to the assessment of spectrographic images,1,6,8,12,18,23−27 which makes the spectrographic vocal assessment even more subjective and hinders the analyses and, consequently, the standardization of results and their understanding by the clinical speech therapist. Thus, the validation of a protocol for spectrographic vocal assessment could provide standardization of assessments, interpretation of their results, and help speech therapists in both clinical practice and scientific research. Assessments based on specific protocols allow the clinician to act in a planned manner, to document procedures, solidifying and sustaining with scientific evidence the clinical practices. Validation of the protocol could also facilitate peer discussion of the analyzed spectrographic vocal aspects.11,16,28 Regarding the protocol development and validation process, there are a number of methodological criteria that must be strictly followed. The elaboration process must be carefully planned so that the instrument can be able to assess and provide data relevant to what it proposes to investigate.28−30 In this sense, evidence of validity allows for more accurate decision making and increases scientific rigor in interpreting instruments.28,31 One of the types of validity, content validity requires the test to present a representative sample of a finite universe of behaviors. To enable a content-validated test, test specifications must be made prior to constructing the items.31,32 Content validity is verified from the analysis of individuals with expertise in the area about the semantic understanding of the items that make up the instrument (clarity) and the relevance/pertinence of these items.12,31 To standardize the aspects that are important in spectrographic analysis and considering the lack of validated instruments in this area, this study aimed to develop and seek evidence of content validity of a SVAP.
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METHODS Study design This is a methodological research, approved by the Ethics Committee on Research with Human Beings of the home institution with the number 1.570.886. Participants To select the volunteers participating in this research, a search was made through the Lattes CNPq database of Voice specialists from different regions of Brazil. Aspects such as formation, production (articles and abstracts), and projects with the subject spectrographic acoustic analysis were considered. Initially, eight judges were selected, but three were excluded because they had no experience with spectrographic analysis specifically, only with acoustic analysis. Finally, the judges selected were five speech therapists, nonauthors of the research (doctors and clinicians), with experience in the field of voice and spectrographic vocal analysis of at least five years, who independently analyzed the items of the proposed protocol.12,32,33 The judges were invited to participate by e-mail and signed an informed consent form. Procedures This research aims to present the development and content validation process of an assessment instrument. This process is subdivided into the development of the instrument, with extensive literature review for the theoretical foundation of the aspects to be assessed by the instrument, and content validation.31 Therefore, the methodological procedures performed were described from this subdivision. Protocol development The SVAP was constructed based on the literature, considering the aspects analyzed in spectrographic vocal assessments and encompassing the largest possible number of parameters.1,6,13,15,16,18,22−26,34−37 SVAP has been used by our research group since the late 1990s. Several spectrographic vocal aspects not validated in the literature and currently used in clinical and speech therapy research were identified and included in a single protocol. Thus, the SVAP was elaborated, consisting of two parts: Broadband Spectrography (BS) and Narrowband Spectrography (NS). Each part with its respective aspects/parameters to be assessed, as well as general written instructions to the evaluators for ease of understanding. To fill the SVAP, a linear analog scale with a score ranging from 0 to 10 cm is used. The assessment of each parameter should be performed by marking a vertical line at any point on the millimeter ruler, according to the observed gradation.2,4,6,8,22,37 In BS, the following parameters are assessed: formant tracing color intensity (1st Formant-F1, 2nd Formant-F2, 3rd Formant-F3, and 4th Formant-F4), of low, medium, and high frequencies and the whole spectrography vocal; tracing regularity at whole vocal spectrogram and at low, medium, and high frequencies; definition, regularity, and bandwidth of
F1, F2, F3, and F4; and antiresonance/damping immediately above F1, at whole vocal spectrography and at low, medium, and high frequencies. In the NS analysis, the following are assessed: tracing color intensity, definition, regularity, and number of harmonics, presence of subharmonics, presence of noise and replacement of harmonics by noise at low, medium, and high frequencies and at whole vocal spectrography.6,8,12,13,15,16,22−26,34,36−39 For purposes of parameter analysis, low frequencies below 1500 Hz, medium frequencies between 1500 and 3000 Hz and high frequencies above 3000 Hz are considered.5,23,25,35,40 The first part of the protocol consists of five items, with their respective subitems, related to BS, detailed below: 1. Tracing color intensity of the four F, low, medium, and high frequencies, and in vocal spectrography as a whole: The tracing color intensity is related to the acoustic signal sound pressure. In spectrography, the degree of darkening present in the trace should be considered, which may vary from black (corresponding to 10 cm), indicating strong signal sound pressure, to light gray, indicating weak sound pressure, or white, suggesting silence. Reduction in the tracing color intensity of some F may suggest nasality, such as F1 or F3, being considered as a result of the addition of damping characteristics on the nasal cavity wall surfaces. Tracing color intensity should be analyzed at each of the four Fs, as well as at low, medium, and high frequencies and in vocal spectrography as a whole.5,26,27,41−43 2. Definition and regularity of the four Fs: The visible, well-demarcated and symmetrical Fs along their temporal representation are considered to be well-defined and regular (corresponding to 10 cm). F that are poorly visible, poorly demarcated, and/or asymmetrical may be considered with an altered definition and F unidentifiable are considered absent with 0 cm marking.22,27,35 3. Tracing regularity at low, medium, and high frequencies and in spectrography as a whole: This aspect deals with the continuity and stability of the vertical striation tracing and relates to the presence of noise or aperiodicity in the sound signal. Thus, a continuous and regular tracing corresponds to 10 cm (total tracing regularity) and a tracing dominated by oscillations, erasures or other types of irregularities corresponds to the total irregularity (0 cm).25,27 4. Bandwidth of the four Fs: The Fs are classified according to their bandwidth, with 10 cm being fully increased and 0 cm being fully decreased F band. F bandwidth represents the effective frequency range of resonator response and increased bandwidth may suggest hypernasality.13,27,44 The increase in F113 and F344 bandwidth is related to the auditory-perceptive characteristic of breathiness. 5. Anti-resonance/damping immediately above F1, at low, medium, and high frequencies and in spectrography as a whole: Described in the literature as an acoustic muffling due to sound dampening, this aspect may be
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related to the direction of sound to the nasal cavity. It corresponds to 10 cm in the domain of erasure spectrography (blank or much lighter than the rest of the spectrography) and 0 cm no identified erasure.27,41,43 The second part of the protocol consists of six items and their respective subitems related to NS: 1. Tracing color intensity of low, medium, and high frequency and in vocal spectrography as a whole: As already mentioned, tracing color intensity refers to sound pressure. The degree of darkening should be considered, which may vary from black (corresponding to 10 cm), indicating strong signal sound pressure, to light gray, indicating weak sound pressure, or white, indicating silence.12,16,26,27 2. Presence of noise at low, medium and high frequencies and in vocal spectrography as a whole: Noise appears in spectrography as a shaded or dotted image and is associated with the aperiodicity of the sound signal. Shading may vary in color intensity from black (corresponding to 10 cm), indicating more noise, to light gray indicating less noise or white, indicating no noise.5,16,26,27,37,40 3. Replacement of harmonics by noise at low, medium, and high frequencies and in vocal spectrography as a whole: Noisy voices can have their harmonics replaced by noise at NS and this can happen especially at high frequencies, showing a voice poor in vocal projection. The absence of harmonics above 3000 Hz in altered voices occurs because aperiodic sound waves are not uniformly amplified, which prevents their multiples from being represented as harmonics in the graph. Thus, the region above 3000 Hz may appear darkened only by the presence of noise.12,40 10 cm for total replacement of harmonic by noise is considered. 4. Definition and regularity of harmonics at low, medium, and high frequencies and in vocal spectrography as a whole: In a normal voice, harmonics (horizontal lines) are expected to be well defined and continuous, showing adequate glottal closure, absence of air escape to phonation, adequate sound pressure, and periodicity in mucosal vibration, showing a regular and well defined tracing (corresponding to 10 cm). When this does not occur, there is a tracing with undefined harmonics, with cuts and or irregularities.16,26,27,35,36,40 5. Number of harmonics at low, medium, and high frequencies and in vocal spectrography as a whole: This relates to the quantity of harmonics present in spectrography in the analyzed frequency range. The 10 cm marking is considered for the complete filling of the spectrographic image by harmonics and 0 cm for the complete absence of harmonics in the NS.26,37 6. Presence of subharmonics in low, medium, and high frequencies and in vocal spectrography as a whole: This is a tracing present between two consecutive harmonics, showing a source of vibration beyond the vocal folds or signifying the presence of noise in the sign. They can be
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a partial or total duplication of harmonics. In this item, 10 cm corresponds to the presence of subharmonics at a whole spectrography and 0 cm to the complete absence of subharmonics in the NS image.16,23,26,34−37 Content validation The five judges received the SVAP by email and were instructed to carefully analyze their items, classified each item of the instrument as "essential" or "not necessary," in others words, if these were needed to be included or not. Each item of the instrument presented a brief orientation (Appendix A) and the judges relating their inclusion with concepts and theoretical considerations. Data analysis was performed by calculating the Content Validity Ratio (CVR) for each item. CVR was obtained by the formula CV = (ne N/2)/(N/2), where he is the number of judges who considered the item as adequate and N represents the total number of judges. Also, to verify agreement among judges, Gwet's first-order agreement coefficient (AC1) statistical calculation was used.45 AC1 agreement was measured by Landis and Koch criteria46 where >0.8 is considered almost perfect, 0.61−0.8 is substantial, 0.41−0.6 is moderate, 0.21−0.4 is regular, and <0.2 is bad. RESULTS The analysis of the SVAP items is shown in Tables 1 and 2 (BS and NS, respectively), with the values of CRV and AC1 Gwet analysis. As for CVR, 24 protocol items had CVR = 1.0 and 25 items had CVR = 0.6. In the AC1 Gwet analysis for SVAP broadband items, agreement was considered substantial and for narrowband items it was almost perfect. The SVAP in its final version was a total of 49 items, subdivided into BS (25 items) and NS (24 items), accompanied by the 10 cm scale for marking items and an initial part with general instructions for filling the protocol (Appendix A). DISCUSSION This study aimed to develop and seek evidence of SVAP content validity, analyzing whether the items that compose it are really clear and relevant, contributing to the standardization of visual analysis and reduction of subjectivity in vocal spectrographic assessment. The results of the Gwet analysis indicated agreement among experts considered substantial for BS (Table 1) and almost perfect for NS (Table 2), reinforcing the evidence of SVAP content validity. In the CVR results (Tables 1 and 2), when only one of the judges did not agree with the protocol item, the index was 0.6, denoting moderate CVR. Therefore, after discussions among the authors and based on the literature, these items were kept. It is noteworthy that for the development of SVAP, the largest possible number of spectrographic vocal aspects were identified and gathered in the available literature and used in clinical and speech therapy research.1,6,13,15,16,18,22−26,34−37 It
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TABLE 1. Analysis of Spectrographic Vocal Assessment Protocol (Broadband Spectrography) Items SVAP Item − Broadband Tracing color intensity of F1 Tracing color intensity of F2 Tracing color intensity of F3 Tracing color intensity of F4 Tracing color intensity of low frequencies Tracing color intensity of medium frequencies Tracing color intensity of high frequencies Tracing color intensity in vocal spectrogram as a whole Definition and regularity of F1 Definition and regularity of F2 Definition and regularity of F3 Definition and regularity of F4 Regularity of vertical striation tracing at low frequencies Regularity of vertical striation tracing at medium frequencies Regularity of vertical striation tracing at high frequencies Regularity of vertical striation tracing in vocal spectrogram as a whole Bandwidth of F1 Bandwidth of F2 Bandwidth of F3 Bandwidth of F4 Anti-resonance/damping immediately above F1 Anti-resonance/damping at low frequencies Anti-resonance/damping at medium frequencies Anti-resonance/damping at high frequencies Anti-resonance/damping in vocal spectrogram as a whole
CVR
AC1
1.0 1.0 1.0 0.6 0.6 0.6 0.6 0.6 1.0 1.0 1.0 0.6 1.0 1.0 1.0 0.6 0.6 0.6 0.6 0.6 0.6 0.6 0.6 0.6 0.6
0.656 [CI = 0.509−0.804]
Gwet’s AC1 Coefficient. Abbreviations: SVAP, spectrographic vocal assessment protocol; CVR, content validity ratio; AC1,Gwet’s AC1 coefficient; F1, 1st formant; F2, 2nd formant; F3, 3rd formant-F3; F4, 4th formant; CI, confidence interval.
is also worth mentioning that the SVAP has been used by our research group since the late 1990s. The elaboration and validation of a protocol to guide the spectrographic vocal assessment by speech therapists is of fundamental importance, aiming to guarantee the quality and standardization of the instruments. Parameters for expanding the possibility of discussion with the literature and greater possibility of scientific advancement in this area.11,28 A recent study has found that visual support of spectrographic imaging significantly increases the reliability of auditory-perceptive voice assessment, as it promote increased inter and intraevaluator agreement.11 This reinforces vocal spectrography as a complementary instrument to other vocal and laryngeal assessments, but it is considered a subjective assessment. It was observed through the literature review that there is a shortage of spectrographic assessment protocols used in research, mainly validated. Only one study found evidence of the content of a narrowband spectrographic vocal analysis protocol. In this study, The Content Validity Index was used to investigate the level of agreement among judges on the overall aspect, items, and domains of the protocol. The proposed protocol was considered comprehensive and the items presented good to excellent content validity for clarity and relevance. After this validation step, the protocol now
has 25 items, all referring only to NS, distributed among the five domains (beginning of emission, temporal aspects of emission, energy distribution in the tracing, harmonic description, and noise distribution in the tracing).12 It is noteworthy that the items of this protocol are also included in the SVAP, plus those of NS and BS considered relevant through the literature review.1,6,13,15,16,18,22−26,34−38,43,44 Another study elaborated the Visual/Spectrographic Analysis Protocol, but it was not validated. The evaluator should classify the following NS parameters: spectrographic tracing shape (regular, irregular, or absent), degree of harmonic darkening (strong, normal, weak, or unobservable), spectrographic tracing stability (stability, instability, or cannot be assessed), presence of noise (present or absent), presence of subharmonics (present or absent), definition of harmonics (the evaluator should write to what frequency the harmonics were defined.26 All these items are present in SVAP. The same protocol mentioned earlier26 was used in another study to assess the effect of visual training on spectrographic analysis. Four hours of training for the judges were performed with the analysis of 100 spectrographs. Regarding intrasubject agreement, the aspects of tracing darkening, tracing stability, presence of sub-harmonics, and definition of harmonics improved and the other aspects maintained almost perfect agreement after training. Regarding
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TABLE 2. Analysis of Spectrographic Vocal Assessment Protocol (Narrowband Spectrography) Items SVAP Item − Narrowband Tracing color intensity of low frequencies Tracing color intensity of medium frequencies Tracing color intensity of high frequencies Tracing color intensity in vocal spectrogram as a whole Presence of noise at low frequencies Presence of noise at medium frequencies Presence of noise at high frequencies Presence of noise in vocal spectrogram as a whole Replacement of harmonics by noise at low frequencies Replacement of harmonics by noise at medium frequencies Replacement of harmonics by noise at high frequencies Replacement of harmonics by noise in vocal spectrogram as a whole Definition and regularity of harmonics at low frequencies Definition and regularity of harmonics at medium frequencies Definition and regularity of harmonics at high frequencies Definition and regularity of harmonics in vocal spectrogram as a whole Number of harmonics at low frequencies Number of harmonics at medium frequencies Number of harmonics at high frequencies Number of harmonics in vocal spectrogram as a whole Presence of subharmonics at low frequencies Presence of subharmonics at medium frequencies Presence of subharmonics at high frequencies Presence of subharmonics in vocal spectrogram as a whole
CVR
AC1
1.0 1.0 1.0 0.6 1.0 1.0 1.0 0.6 1.0 1.0 1.0 0.6 1.0 1.0 1.0 0.6 0.6 1.0 0.6 0.6 0.6 1.0 1.0 0.6
0.848 [CI = 0.742−0.953]
Gwet’s AC1 Coefficient. Abbreviations: SVAP, spectrographic vocal assessment protocol; CVR, content validity ratio; AC1, Gwet’s AC1 coefficient; CI, confidence interval.
intersubject agreement, the aspects of tracing stability and the presence of subharmonics improved, and the noise presence aspect worsened after training.16 According to the literature, the parameters of BS generally assessed are: F intensity;8,10,27,47 tracing color intensity;8,10,27,47 presence of noise;8,10,27,47 F bandwidth;13,27,44 definition of F;8,10,27,47 tracing regularity,8,10,27,47 and antiresonance/ damping.27,41 In the studies with NS, the following aspects were analyzed: tracing color intensity;2,8,10,12,16,22,26,27,37,47 presence of noise between harmonics;4,8,10,12,16,22,26,27,37,47 replacement of harmonics by noise;8,10,12,47 definition of harmonics;2,8,10,12,16,26,27,47 tracing regularity;4,8,10,12,16,22, 26,27,37,47 number of harmonics,2,4,8,10,12,16,22,26,37,47 and presence of subharmonics.2,4,8,10,16,22,26,37,47 The literature reports that the lower F, F1, and F2, are related to the height and anteriority of the tongue within the oral cavity, determining the quality and identity of the vowels. The upper F F3, F4, and F5 are related to vocal quality. This is because the frequencies of the lower F are related to the tongue configuration in the vocal tract and the upper F to the vocal tract length and dimension in and around the larynx. The upper F is more evident in the voices of singers and actors, because their voices have higher quality and projection. Therefore, voices of normal speakers, who do not have vocal training, do not usually have good definition of upper F, and F4 and F5 may not be observable.10,27
The bandwidth of F represents the effective frequency range of resonator response, that is, the frequency range around which a resonator will respond to a stimulus.44 Increased bandwidth may suggest hypernasality.27,44 Still, a recent study related the increase in F113 and F344 bandwidth with the perceptual characteristic of breathiness. The phenomenon called “antiresonance or damping” is described in the literature as an acoustic dampening due to sound deadening. This aspect may be related to the direction of sound to the nasal cavity, where the tissues are softer, causing energy loss mainly in the higher harmonics. The phenomenon is also known in the literature as “damping, drop in intensity, or negative resonance in high frequencies.”27,41,43 In a group of young adult men with unaffected larynx and no vocal complaints, antiresonance/damping was considered median, that is, between very and little present, when judged by three speech therapists with voice experience.27 A study with patients undergoing septoplasty hypothesized that after surgery there would be a decrease in antiresonance/damping and an increase in voice amplitude or energy, but there was no statistical difference between preand postoperative moments.43 High frequency erasures besides suggesting nasality also indicate breathiness and low loudness.27,43,44 The contraction of the laryngeal adductor musculature increases the phonatory effort at the beginning of emission, the resistance to air flow and the closed phase of the glottic
ARTICLE IN PRESS 6 cycle. This generates increased tracing energy at high frequencies due to increased sound pressure, being common in cases of vocal fold mass injury.12 The reduction in tracing color intensity may be related to inefficient glottic closure, inefficient use of resonance cavities, and/or decreased sound pressure.12,26,27,41,42 The presence of noise on spectrography is an important indicator of the presence of vocal and/or laryngeal alterations, either throughout the emission or in specific sections.12 The replacement of harmonics by noise is related to aerodynamic, neurological, and biomechanical issues that cause signal aperiodicity. The more deviated the vocal signal, the greater the replacement of the harmonic structure by noise.12,27 The presence of well-defined regular harmonics is a characteristic of healthy voices. It indicates good glottal coaptation and greater regularity in vocal fold mucosa vibration. When spectrographic tracing appears less defined, it may suggest the beginning of vocal alteration development.8 The tracing is considered irregular when fluctuations in the behavior of energy and noise along the emission are observed, related to the fluctuation in the emission.11,12 The presence of a rich series of harmonics in spectrography indicates adequate glottal closure and vocal projection, while altered voices usually present harmonics only up to the 2000 Hz range.40 High frequency harmonics are observed more in individuals who make professional use of the voice, such as actors, singers, and teachers, and in people who have performed vocal training, indicating vocal projection and high loudness. Thus, decreasing the number of harmonics in this frequency range does not necessarily indicate vocal alteration, but may be a typical characteristic of untrained voices.12,27 The subharmonic is usually associated with the vibratory irregularity of the vocal fold mucosa, and may be related to the presence of roughness present at emission and/or more intense vocal deviation, being easily identified in spectrography. The presence of subharmonics may also show a source of vibration beyond the vocal folds.16,23,26,34−37 It is noteworthy that these were some of the studies that served as theoretical basis for the elaboration of SVAP, encompassing the largest possible number of parameters commonly used in clinical and speech therapy research, but without standardization.1,6,13,15,16,18,22−26,34−38,43,44,47 SVAP condenses and outlines important concepts of spectrographic evaluation that allow detailed and more objective analysis of the images, helping the clinician and researcher. The protocol may serve to characterize the voice of a patient or populations, as well as to track therapy outcomes and as visual feedback to patients. As a limitation of this study, there is a shortage of literature for further discussion of the results in which there is only a narrowband protocol with content validity.12 Further research should be conducted using SVAP in different populations, as well pre- and post-treatment groups can be compared using evidence of sensitivity to provide normative data for various circumstances.
Journal of Voice, Vol. &&, No. &&, 2019
CONCLUSION SVAP presents evidence of satisfactory content validity. The final version of the protocol, after this validation step, has a total of 49 items, being 25 in BS and 24 in NS. Acknowledgements This study was financed in part by the Coordena¸c ~ ao de Aperfei¸c oamento de Pessoal de Nível Superior - Brasil (CAPES) - Finance Code 001. SUPPLEMENTARY MATERIALS Supplementary material associated with this article can be found in the online version at https://doi.org/10.1016/j. jvoice.2019.12.008. APPENDIX A SPECTROGRAPHIC VOCAL ASSESSMENT PROTOCOL Instructions: Using a linear analog scale with a score ranging from 0 to 10 cm, the evaluation of each aspect of the protocol should be carried out by marking a vertical line at any point on the ruler, according to the gradation observed at each aspect. For purposes of parameter analysis, low frequencies below 1500 Hz, medium frequencies between 1500 and 3000 Hz, and high frequencies above 3000 Hz should be considered. BROADBAND VOCAL SPECTROGRAPHY 1. Color intensity of tracing In this item, zero corresponds to the total colorlessness of the trace, and 10 corresponds to the extreme color intensity of the spectrographic trace.
ARTICLE IN PRESS Gabriele Rodrigues Bastilha, et al
Development and Evidence of Content Validity
2. Definition and regularity of formants In this item, zero corresponds to the total irregularity and indefinition and 10 to the maximum regularity and definition of the formants.
3. Trace regularity In this item, zero corresponds to the total irregularity and 10 to the maximum regularity of the trace.
4. Bandwidth In this item, zero corresponds to fully reduced/absent and 10 to fully increased.
5. Anti-resonance/damping In this item, zero corresponds to the total absence of erasures (blanks or much lighter than the rest in the spectrography) and 10 to the presence/domain of the erasure spectrography window.
7
NARROWBAND VOCAL SPECTROGRAPHY 1. Color intensity of tracing In this item, zero corresponds to the total colorlessness of the trace, and 10 corresponds to the extreme color intensity of the spectrographic trace.1.1 Of the low frequencies
2. Presence of noise In this item, zero corresponds to the total absence of noise and 10 to the maximum noise (shaded image) present.
3. Noise replacement of harmonics In this item, zero corresponds to the absence of noise harmonic replacement and 10 to the total noise harmonic replacement.
4. Harmonic definition and regularity In this item, zero corresponds to the total irregularity and indefinition and 10 to the total regularity and definition of the harmonics.
ARTICLE IN PRESS 8 5. Number of harmonics In this item, zero corresponds to the absence of harmonics and 10 to the complete filling of the harmonic spectrographic image.
6. Presence of subharmonics In this item, zero corresponds to the absence of subharmonics and 10 to the presence of subharmonics throughout the spectrography.
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