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English distinction in normal and language disordered children
Journal of Phonetics (1981) 9, 437-444
Voice onset time: the development of Spanish/English distinction in normal and language disordered children Joanne A. Konefal and Joann Fokes School of Hearing and Speech Sciences, Lindley Hall, Ohio University , Athens, Ohio 45701, U.S.A . Received lOth October 1980
Abstract:
Voice onset time ( VOT) values for the six English and Spanish stops were measured for three Spanish speaking children , age four, seven, and ten years, who learned English as a second language. The two younger children had progressed normally in language development while the ten year old had a delayed onset. Spectrograms of ten tokens of each of six words in English and in Spanish were analyzed. VOT values in both languages for the younger children were significantly different. A developmental trend was noted in that the seven year old had acquired the Spanish prevoiced stops while the four year old employed the short lag range. Both had acquired the short lag range for voiceless Spanish stops. The ten year old language delayed child, however, employed the VOT values of English for the Spanish voicing categories.
Introduction Voice onset time (VOT) is a widely used measure for distinguishing between voiced con· trasts in languages. Lisker & Abramson (I 971) stated that VOT is the "single most effective measure for classifying stops into different phonetic categories with respect to voicing". VOT is defined as the time interval between the release of stop occlusion and the onset of vocal fold oscillation. Voice onset time can be easily measured from spectrograms of consonant initial syllables. Linguists have claimed that the voicing parameter is a primary phonetic dimension for distinguishing among homorganic stops. In a cross language study, Lisker & Abramson (I 964) found that VOT is a reliable parameter for differentiating the voicing contrasts in a number of languages. There are three relatively specific ranges of VOT for initial stop consonant productions. In the voicing lead range, voicing precedes the release of the stop and these stops have a negative VOT value. Voicing begins at 0 to + 20 ms after the stop release in the short voicing lag range and + 60 ms after the release for the long voicing lag range (Kewley-Port & Preston, 1974). Many studies have suggested early development of perception of these VOT boundaries (Eimas, 1975; Morse , 1972; Moffitt, 1971). Research found that young infants can discriminate differences in phonetic consonant categories for voicing and place of articulation. Trehub & Robinovitch (I 972) found that four month old infants from English speaking environments had started to develop linguistic categories for bilabial stops that resembled adult English phonemic categories. Zlatin & Koenigsknecht (1975) observed that the voiced/ voiceless category boundary in identification tasks become narrower for English-speaking 0095-4470/81/040437 + 08 $02.00/0
© 1981 Academic Press Inc. (London) Ltd.
438
J. A. Konefal and J. Fakes
children as they progress from two years to six years to adulthood. However, Abramson & Lisker (1970) studies of adult listeners have revealed that the prevoiced/voiced boundary is generally not discriminated by English-speaking adults , suggesting that these category boundaries may disappear developmentally in the absence of appropriate use. Fewer investigations have been done in the area of the development of VOT production. Zlatin & Koenigsknecht (1976) found that developmental changes in the production of word initial stops at all points of articulation occurred between ages two, six, and adults. They reported that until the age of three , children's productions were unimodal in the short lag range of the VOT continum and after age three , bimodal VOT distributions start to emerge. There has been interest in the development of VOT categories in the production of bilingual children's speech. Preston et al. (1967) suggested that although at 12 months English and Lebanese infants produced apical stop consonants in the short lag range, by the age of two these children began to exhibit values for voiced/voiceless stops which were phonologically appropriate to their own specific languages. Bond et at. (1980) compared the VOT values of Spanish and English words produced by two Spanish speaking siblings, one language delayed and one normal. They concluded that the normal child (age four) followed the developmental pattern of extending the VOT durations from the short voicing lag range to the pre-voiced and long lag ranges. However, the language disordered subject (age seven) was late in developing the bimodal VOT distribution in that her VOT productions were confined to the short lag range for both Spanish and English. Little is known concerning the developmental aspects of voice onset time in language disordered children. Suggestions have been made by Menyuk & Looney (1972) and Panagos (1974) that children who are delayed in syntactic development may also have difficulty in producing phonological structures. Bond eta!. (1980) data seem to suggest that a delay in the development of the acoustic parameter of VOT is a function of an overall profile of delayed language development. The purpose of this study was first to investigate the effect of learning English on voice onset time values of word initial stop consonants in Spanish children's speech. Secondly , the initial stop consonant production of a language disordered child was compared to her normally developing sisters. More specifically, three experimental questions were posed: first , after three years exposure to English, were the VOT values for Spanish and English different; secondly, was there a developmental difference in VOTvalues among the children; and thirdly, were the productions of the language disordered child different from those of two normally developing sisters.
Method Subjects The subjects were three sisters aged four, seven, and ten. The siblings were raised in Venezuela, South America by monolingual Spanish speaking parents until the family moved to the United States in 1977. The parents continued to speak Spanish in the home, but all children received exposure to English in school in Athens, Ohio. Subject one, aged four, was a verbal friendly child whose English language level appeared to be age approp1iate . She was reported to comprehend Spanish but to have a limited expressive vocabulary. Subject two, aged seven, attended first grade in Athens City Schools and was reported by her teachers to be on academic level with a good command of the English language. Her parents reported that she had acquired Spanish normally before
439
Spanish/ English voice onset time distinction
entering the states. Subject three , aged ten, was the language disordered subject. Her parents reported that she had spoken Spanish very little and that they were concerned about her language abilities prior to the move to the United States. After coming to this country in 1977, she had been enrolled at the Ohio University Hearing and Speech Clinic. Initial progress was slow but after six months of therapy, she began to make rapid progress in acquiring English. At the time of the study, she was described as manifesting a pragmatic disorder with difficulty in staying on topic, contributing relevant information, and recalling information. Her syntactic abilities were age appropriate in that she was using relative clauses and compound sentence structures. Speech was rated as intelligible when she maintained the topic of conversation. Stimuli and apparatus Three minimal pairs of Spanish and English words with initial labial, dental, and velar stops were pictured on 3 x 5 cards. The vowels were matched as well as possible for the Spanish and English words containing the homorganic stops. The stimulus words were: paiio-baiio, Paul-ball, tia-dia , tear-deer, cama-gama, coat-goat. Most of the words were familiar to the children and the less familiar word gama was taught before recording to give it meaning. A Sony tape recorder was used to record each subject's utterances. Spectrograms of each token were made on a 700 Series Voice Identification spectrograph. Procedure Each child was tested individually in a private therapy room at Ohio University Hearing and Speech Oinic . Native speakers of each language presented their respective stimuli during separate sessions. The children were required to produce ten tokens of 12 words by means of a delayed imitation task. Wide band spectrograms employing a 500 Hz fllter were made of the subject's productions and the duration of voice onset time of the initial stop consonants in each word was measured. Spectrographically, VOT was measured from the burst of energy indicating release of the stop to the onset of vocal fold vibration marked by regulary spaced vertical striations. A 3000 Hz variable band pass filter was used before spectrographic recording to eliminate ambient tape noise.
Results and discussion Each child produced ten tokens of the 12 stimulus words. VOT values were computed for the voiced and voiceless Spanish and English initial stops. Data were grouped according to the voiced/voiceless category for each language and subject. T tests were performed to determine if the voiced/voiceless distinction maintained was significant between languages for each subject. Table I presents the T test values for the VOT distinctions between languages. Table 1 T test values for Spanish and English voiced/voiceless categories produced by s,s2s3 (t = 3.659,p < 0.001)
sl s2
(age 4) (age 7)
s3 (age 10 language disordered) *Not significant.
Spanish/English voiced
Spanish/English voiceless
6.6 9 4.52
4.45 9.09
3 .62*
2.53*
J. A. Konefal and J. Fakes
440
For both normal subjects, S 1 and S 2 , the Spanish and English VOT values for both the voiced stop category and the voiceless stop category were significantly different. (p < 0.001) The language disorder child, S 3 , did not maintain a distinction between either the Spanish-English voiced category or the Spanish-English voiceless category. To compliment the results obtained from the statistical analysis, histograms showing the range of VOT values for Spanish and English voiced and voiceless stops for each subject were drawn. Figure 1 presents the distribution of VOT values for English voiced and voiceless stops for S 1 . 30
25 20
2lE
15
z"
10 5
0
I
II
40
I:
80
120
160
200
240
280
Voice onset time
Figure 1
Histogram showing the distribution of VOTvalues for English voiced (solid line) and English voiceless (dotted line) as produced by S 1 (age 4).
S 1 maintained the voicing contrast in English with the majority of voiced VOTvalues in the short lag range. The voiceless category was stable with the mean VOT value clustering within the 80 to 120 ms range. S 1 's distribution of VOT values for Spanish voiced and voiceless stops is presented in Fig. 2. 30 25 20
"'
.0
§
15
z
10 5
0
40
80
120
160
200
Voice onset time
Figure 2
Histogram showing the distribution of VOT values for Spanish voiced (solid line) and Spanish voiceless (dotted line) as produced by S 1 (age 4).
441
Spanish/English voice onset time distinction
S 1 's distribution of Spanish voiced stops was only in the short lqg range and the Spanish voiceless stops were clustered between 20 to 80 ms. It appeared that the range for the Spanish voiceless stops was approximating the short lag range because the distribution was not as wide as for the English voiceless stops (Fig. 1). However, this subject, aged four, did not produce Spanish voiced stops in the pre-voicing range. Kewly-Port & Preston (1974) suggested that the articulatory adjustments necessary to produce a stop in the short lag range were less complex than the articulatory control needed to produce prevoiced stops. Figure 3 presents the distribution of VOT values for the English voiced/voiceless category for s2 age seven. 30 25 20
~ §
15
z
10 5
0
J
40
80
120
160
200
Voice onset time
Figure 3
Histogram showing the distribution of VOT values for English voiced (solid line) and English voiceless (dotted line) as produced by S2 (age 7). 30,-------------------------------~
25 20
a;
-"
E :>
15
z
0
40
Voice onset time
Figure4
Histogram showing the distribution of VOT values for Spanish voiced (solid line) and Spanish voiceless (dotted line) as produced by S 2 (age 7).
S 2 maintained the English voiced/voiceless contrast with the voiced stops produced in the short lag range and the voiceless stops clustered around 40-60 ms. Figure 4 shows the distribution of VOT values for the Spanish voiced/voiceless categories for this subject. S 2 prevoiced her Spanish voiced stops while all of her productions for the Spanish voiceless stops were in the short lag range. Thus in contrast to her four year old
J. A . Konefal and J. Fakes
442
sister, this seven year old used the VOT values in the short voicing lag range, prevoiced, and long voicing lag ranges. She had acquired the voiced/voiceless distinctions in both Spanish and English. The VOT distribution for English voiced/voiceless category for S 3 , the language disordered child, is presented in Fig. 5. 30 25 20
:;;
-"
~ z
15 10 5
I I I
II
I
40
0
80
120
160
Voice onset time
Figure 5
Histogram showing the distribution of VOT values for English voiced (solid line) and English voiceless (dotted line) as produced by S 3 (language disordered).
30 25 20
:;; -"
15
~ z
IO L
5
I
I
-120
,I -80
-40
0
40
80
120
160
Voice onset ti me
Figure 6
Histogram showing the distribution of VOT values for Spanish voiced (solid line) and Spanish voiceless (dotted line) as produced by S 3 (language disordered) .
The language disordered child's VOT ranges appeared to overlap for the voiced/voiceless category. Some of the voiced category extended into the long lag range, that is, around 40-70 ms. The voiceless or long lag range cluste rs were between 40 and 80 ms. She could be developing a clearer distinction between the voiced/voiceless category in English. S 3 's range of VOT for the voiced/voiceless Spanish category is presented in Fig. 6. There was some prevoicing for the Spanished voiced category but the majority of VOT distribution fell in the short lag range. Also the Spanish voiceless category extended from the short lag range into the long lag range . Here again , there did not appear to be a clear
Spanish/English voice onset time distinction
443
distinction between the Spanish voiced/voiceless category. The language disordered subject (C.A. 10) seemed to be late in developing a bimodal VOT distribution, as the range of her VOT productions were predominately confined to the short voicing lag range for both Spanish and English. This delay in the appropriate VOT values may be a manifestation of her language disorder. The present data support results found by Bond et al. (1980) who found that their normal subject, now age seven (S 2 ) was following the development pattern of extending the VOT durations from the short voicing lag range to the prevoiced and long voicing lag ranges. The present data indicate that S 2 has the voiced/voiceless contrast in Spanish and English. Bond et al. found that the language disordered child's productions, then seven years old, were confined to the short voicing lag range for both Spanish and English. After three years , the language disordered child was beginning to extend the range into the long lag range for both Spanish and English voiceless stops with only slight evidence for prevoiced Spanish stops. There is a development of word initial stops being produced in the short lag range, progressing to an overlap of VOT distribution of voiced/ voiceless stops in the short and long lag ranges, and then some productions in the prevoicing range. These results seem to agree with reported data on the development of the voicing distinction in children (Zlatin & Koenigsknecht, 1976). Conclusions From the results of this study , two conclusions can be made . First, there is support for a developmental pattern of VOT durations from a short lag range, to a long lag range, to a pre-voiced range for Spanish-English bilinguals who had sufficient exposure to both languages. Secondly, a child who has a language disorder may also manifest a delay in language specific acoustic parameters of speech. We would like to thank Dr. Z. S. Bond for her remarks and suggestions. We also acknowledge Miguel Farias for his assistance in data collection. References Abramson, A. & Lisker, L. (1973). Voice-timing perception in Spanish word-initial stops. Journal of Phonetics, 1, 1-18. Abramson, A. & Lisker, L. (1967). Discriminability along the voicing continuum: Cross language tests. Proceedings of the Sixth International Congress of Phonetic Sciences, Prague, pp. 569-573. Prague: Academia. ·· Bond, Z. S., Eddey, J. & Bermejo, J. (1980) . VOT del Espaii.ol to English: Comparison of!anguagedisordered and normal child. Journal of Phonetics, 8, 287-291. Eimas, P. (1975). Speech perception in early infancy. In Infant Perception: From Sensation to Cognition. Vol. II (L. Cohen and P. Salapatek eds), pp. 193-231. New York: Academic Press. Kewly-Port, D. & Preston, M. (1974). Early apical stop production: A voice onset time analysis. Journal of Phonetics, 2, 195-210. Lisker, L. & Abramson, A. (1964). A cross-language study of voicing in initial stops; Acoustical measurements. Word, 20, 384--422. Lisker, L. & Abramson, A. (1971). Distinctive features and laryngeal control. Language, 4 7, 770. Menyuk, P. & Looney, P. (1972). Relationships among components of the grammar in language disorders. Journal of Speech and Hearing Research, 15, 395-406. Moffitt, A. (1971). Consonant cue perception by twenty to twenty-four week old infants. Child Development,42, 717-731. Morse, P. (1972). The discrimination of speech and nonspeech stimuli in early infancy. Journal of Experimental Child Psychology , 14,477-492. Panagos, J. (1974). Persistance of the open syllable reinterpreted as a symptom of a language disorder. Journal of Speech and Hearing Research, 39, 23-31. Preston, M., Yeni-Komshian, G. & Stark, R. (1967). Voicing in initial stop consonants produced by children in the prelinguistic period from different language communities. Johns Hopkins University School of Medicine, Annual Report of Neurocommunications Laboratory, 2, 305-323.
444
J. A. Konefal and J. Fakes
Trehub, S. & Rabinovitch, M. (1972). Auditory-linguistic sensitivity in early infancy. Developmental Psychology, 6, 74-77. Zlatin, M. & Koenigsknecht, R. (1976). Development of the voicing contrast. A comparison of voice onset time values in stop perception and production. Journal of Speech and Hearing Research, 19, 93- 111. Zlatin, M. & Koenigsknecht, R. (1975). Development of the voicing contrast: perception of stop consonants. Journal of Speech and Hearing Research, 18,541-553.
Voice onset time: the development of Spanish/English distinction in normal and language disordered children Joanne A. Konefal and Joann Fokes School of Hearing and Speech Sciences, Lindley Hall, Ohio University , Athens, Ohio 45701, U.S.A . Received lOth October 1980
Abstract:
Voice onset time ( VOT) values for the six English and Spanish stops were measured for three Spanish speaking children , age four, seven, and ten years, who learned English as a second language. The two younger children had progressed normally in language development while the ten year old had a delayed onset. Spectrograms of ten tokens of each of six words in English and in Spanish were analyzed. VOT values in both languages for the younger children were significantly different. A developmental trend was noted in that the seven year old had acquired the Spanish prevoiced stops while the four year old employed the short lag range. Both had acquired the short lag range for voiceless Spanish stops. The ten year old language delayed child, however, employed the VOT values of English for the Spanish voicing categories.
Introduction Voice onset time (VOT) is a widely used measure for distinguishing between voiced con· trasts in languages. Lisker & Abramson (I 971) stated that VOT is the "single most effective measure for classifying stops into different phonetic categories with respect to voicing". VOT is defined as the time interval between the release of stop occlusion and the onset of vocal fold oscillation. Voice onset time can be easily measured from spectrograms of consonant initial syllables. Linguists have claimed that the voicing parameter is a primary phonetic dimension for distinguishing among homorganic stops. In a cross language study, Lisker & Abramson (I 964) found that VOT is a reliable parameter for differentiating the voicing contrasts in a number of languages. There are three relatively specific ranges of VOT for initial stop consonant productions. In the voicing lead range, voicing precedes the release of the stop and these stops have a negative VOT value. Voicing begins at 0 to + 20 ms after the stop release in the short voicing lag range and + 60 ms after the release for the long voicing lag range (Kewley-Port & Preston, 1974). Many studies have suggested early development of perception of these VOT boundaries (Eimas, 1975; Morse , 1972; Moffitt, 1971). Research found that young infants can discriminate differences in phonetic consonant categories for voicing and place of articulation. Trehub & Robinovitch (I 972) found that four month old infants from English speaking environments had started to develop linguistic categories for bilabial stops that resembled adult English phonemic categories. Zlatin & Koenigsknecht (1975) observed that the voiced/ voiceless category boundary in identification tasks become narrower for English-speaking 0095-4470/81/040437 + 08 $02.00/0
© 1981 Academic Press Inc. (London) Ltd.
438
J. A. Konefal and J. Fakes
children as they progress from two years to six years to adulthood. However, Abramson & Lisker (1970) studies of adult listeners have revealed that the prevoiced/voiced boundary is generally not discriminated by English-speaking adults , suggesting that these category boundaries may disappear developmentally in the absence of appropriate use. Fewer investigations have been done in the area of the development of VOT production. Zlatin & Koenigsknecht (1976) found that developmental changes in the production of word initial stops at all points of articulation occurred between ages two, six, and adults. They reported that until the age of three , children's productions were unimodal in the short lag range of the VOT continum and after age three , bimodal VOT distributions start to emerge. There has been interest in the development of VOT categories in the production of bilingual children's speech. Preston et al. (1967) suggested that although at 12 months English and Lebanese infants produced apical stop consonants in the short lag range, by the age of two these children began to exhibit values for voiced/voiceless stops which were phonologically appropriate to their own specific languages. Bond et at. (1980) compared the VOT values of Spanish and English words produced by two Spanish speaking siblings, one language delayed and one normal. They concluded that the normal child (age four) followed the developmental pattern of extending the VOT durations from the short voicing lag range to the pre-voiced and long lag ranges. However, the language disordered subject (age seven) was late in developing the bimodal VOT distribution in that her VOT productions were confined to the short lag range for both Spanish and English. Little is known concerning the developmental aspects of voice onset time in language disordered children. Suggestions have been made by Menyuk & Looney (1972) and Panagos (1974) that children who are delayed in syntactic development may also have difficulty in producing phonological structures. Bond eta!. (1980) data seem to suggest that a delay in the development of the acoustic parameter of VOT is a function of an overall profile of delayed language development. The purpose of this study was first to investigate the effect of learning English on voice onset time values of word initial stop consonants in Spanish children's speech. Secondly , the initial stop consonant production of a language disordered child was compared to her normally developing sisters. More specifically, three experimental questions were posed: first , after three years exposure to English, were the VOT values for Spanish and English different; secondly, was there a developmental difference in VOTvalues among the children; and thirdly, were the productions of the language disordered child different from those of two normally developing sisters.
Method Subjects The subjects were three sisters aged four, seven, and ten. The siblings were raised in Venezuela, South America by monolingual Spanish speaking parents until the family moved to the United States in 1977. The parents continued to speak Spanish in the home, but all children received exposure to English in school in Athens, Ohio. Subject one, aged four, was a verbal friendly child whose English language level appeared to be age approp1iate . She was reported to comprehend Spanish but to have a limited expressive vocabulary. Subject two, aged seven, attended first grade in Athens City Schools and was reported by her teachers to be on academic level with a good command of the English language. Her parents reported that she had acquired Spanish normally before
439
Spanish/ English voice onset time distinction
entering the states. Subject three , aged ten, was the language disordered subject. Her parents reported that she had spoken Spanish very little and that they were concerned about her language abilities prior to the move to the United States. After coming to this country in 1977, she had been enrolled at the Ohio University Hearing and Speech Clinic. Initial progress was slow but after six months of therapy, she began to make rapid progress in acquiring English. At the time of the study, she was described as manifesting a pragmatic disorder with difficulty in staying on topic, contributing relevant information, and recalling information. Her syntactic abilities were age appropriate in that she was using relative clauses and compound sentence structures. Speech was rated as intelligible when she maintained the topic of conversation. Stimuli and apparatus Three minimal pairs of Spanish and English words with initial labial, dental, and velar stops were pictured on 3 x 5 cards. The vowels were matched as well as possible for the Spanish and English words containing the homorganic stops. The stimulus words were: paiio-baiio, Paul-ball, tia-dia , tear-deer, cama-gama, coat-goat. Most of the words were familiar to the children and the less familiar word gama was taught before recording to give it meaning. A Sony tape recorder was used to record each subject's utterances. Spectrograms of each token were made on a 700 Series Voice Identification spectrograph. Procedure Each child was tested individually in a private therapy room at Ohio University Hearing and Speech Oinic . Native speakers of each language presented their respective stimuli during separate sessions. The children were required to produce ten tokens of 12 words by means of a delayed imitation task. Wide band spectrograms employing a 500 Hz fllter were made of the subject's productions and the duration of voice onset time of the initial stop consonants in each word was measured. Spectrographically, VOT was measured from the burst of energy indicating release of the stop to the onset of vocal fold vibration marked by regulary spaced vertical striations. A 3000 Hz variable band pass filter was used before spectrographic recording to eliminate ambient tape noise.
Results and discussion Each child produced ten tokens of the 12 stimulus words. VOT values were computed for the voiced and voiceless Spanish and English initial stops. Data were grouped according to the voiced/voiceless category for each language and subject. T tests were performed to determine if the voiced/voiceless distinction maintained was significant between languages for each subject. Table I presents the T test values for the VOT distinctions between languages. Table 1 T test values for Spanish and English voiced/voiceless categories produced by s,s2s3 (t = 3.659,p < 0.001)
sl s2
(age 4) (age 7)
s3 (age 10 language disordered) *Not significant.
Spanish/English voiced
Spanish/English voiceless
6.6 9 4.52
4.45 9.09
3 .62*
2.53*
J. A. Konefal and J. Fakes
440
For both normal subjects, S 1 and S 2 , the Spanish and English VOT values for both the voiced stop category and the voiceless stop category were significantly different. (p < 0.001) The language disorder child, S 3 , did not maintain a distinction between either the Spanish-English voiced category or the Spanish-English voiceless category. To compliment the results obtained from the statistical analysis, histograms showing the range of VOT values for Spanish and English voiced and voiceless stops for each subject were drawn. Figure 1 presents the distribution of VOT values for English voiced and voiceless stops for S 1 . 30
25 20
2lE
15
z"
10 5
0
I
II
40
I:
80
120
160
200
240
280
Voice onset time
Figure 1
Histogram showing the distribution of VOTvalues for English voiced (solid line) and English voiceless (dotted line) as produced by S 1 (age 4).
S 1 maintained the voicing contrast in English with the majority of voiced VOTvalues in the short lag range. The voiceless category was stable with the mean VOT value clustering within the 80 to 120 ms range. S 1 's distribution of VOT values for Spanish voiced and voiceless stops is presented in Fig. 2. 30 25 20
"'
.0
§
15
z
10 5
0
40
80
120
160
200
Voice onset time
Figure 2
Histogram showing the distribution of VOT values for Spanish voiced (solid line) and Spanish voiceless (dotted line) as produced by S 1 (age 4).
441
Spanish/English voice onset time distinction
S 1 's distribution of Spanish voiced stops was only in the short lqg range and the Spanish voiceless stops were clustered between 20 to 80 ms. It appeared that the range for the Spanish voiceless stops was approximating the short lag range because the distribution was not as wide as for the English voiceless stops (Fig. 1). However, this subject, aged four, did not produce Spanish voiced stops in the pre-voicing range. Kewly-Port & Preston (1974) suggested that the articulatory adjustments necessary to produce a stop in the short lag range were less complex than the articulatory control needed to produce prevoiced stops. Figure 3 presents the distribution of VOT values for the English voiced/voiceless category for s2 age seven. 30 25 20
~ §
15
z
10 5
0
J
40
80
120
160
200
Voice onset time
Figure 3
Histogram showing the distribution of VOT values for English voiced (solid line) and English voiceless (dotted line) as produced by S2 (age 7). 30,-------------------------------~
25 20
a;
-"
E :>
15
z
0
40
Voice onset time
Figure4
Histogram showing the distribution of VOT values for Spanish voiced (solid line) and Spanish voiceless (dotted line) as produced by S 2 (age 7).
S 2 maintained the English voiced/voiceless contrast with the voiced stops produced in the short lag range and the voiceless stops clustered around 40-60 ms. Figure 4 shows the distribution of VOT values for the Spanish voiced/voiceless categories for this subject. S 2 prevoiced her Spanish voiced stops while all of her productions for the Spanish voiceless stops were in the short lag range. Thus in contrast to her four year old
J. A . Konefal and J. Fakes
442
sister, this seven year old used the VOT values in the short voicing lag range, prevoiced, and long voicing lag ranges. She had acquired the voiced/voiceless distinctions in both Spanish and English. The VOT distribution for English voiced/voiceless category for S 3 , the language disordered child, is presented in Fig. 5. 30 25 20
:;;
-"
~ z
15 10 5
I I I
II
I
40
0
80
120
160
Voice onset time
Figure 5
Histogram showing the distribution of VOT values for English voiced (solid line) and English voiceless (dotted line) as produced by S 3 (language disordered).
30 25 20
:;; -"
15
~ z
IO L
5
I
I
-120
,I -80
-40
0
40
80
120
160
Voice onset ti me
Figure 6
Histogram showing the distribution of VOT values for Spanish voiced (solid line) and Spanish voiceless (dotted line) as produced by S 3 (language disordered) .
The language disordered child's VOT ranges appeared to overlap for the voiced/voiceless category. Some of the voiced category extended into the long lag range, that is, around 40-70 ms. The voiceless or long lag range cluste rs were between 40 and 80 ms. She could be developing a clearer distinction between the voiced/voiceless category in English. S 3 's range of VOT for the voiced/voiceless Spanish category is presented in Fig. 6. There was some prevoicing for the Spanished voiced category but the majority of VOT distribution fell in the short lag range. Also the Spanish voiceless category extended from the short lag range into the long lag range . Here again , there did not appear to be a clear
Spanish/English voice onset time distinction
443
distinction between the Spanish voiced/voiceless category. The language disordered subject (C.A. 10) seemed to be late in developing a bimodal VOT distribution, as the range of her VOT productions were predominately confined to the short voicing lag range for both Spanish and English. This delay in the appropriate VOT values may be a manifestation of her language disorder. The present data support results found by Bond et al. (1980) who found that their normal subject, now age seven (S 2 ) was following the development pattern of extending the VOT durations from the short voicing lag range to the prevoiced and long voicing lag ranges. The present data indicate that S 2 has the voiced/voiceless contrast in Spanish and English. Bond et al. found that the language disordered child's productions, then seven years old, were confined to the short voicing lag range for both Spanish and English. After three years , the language disordered child was beginning to extend the range into the long lag range for both Spanish and English voiceless stops with only slight evidence for prevoiced Spanish stops. There is a development of word initial stops being produced in the short lag range, progressing to an overlap of VOT distribution of voiced/ voiceless stops in the short and long lag ranges, and then some productions in the prevoicing range. These results seem to agree with reported data on the development of the voicing distinction in children (Zlatin & Koenigsknecht, 1976). Conclusions From the results of this study , two conclusions can be made . First, there is support for a developmental pattern of VOT durations from a short lag range, to a long lag range, to a pre-voiced range for Spanish-English bilinguals who had sufficient exposure to both languages. Secondly, a child who has a language disorder may also manifest a delay in language specific acoustic parameters of speech. We would like to thank Dr. Z. S. Bond for her remarks and suggestions. We also acknowledge Miguel Farias for his assistance in data collection. References Abramson, A. & Lisker, L. (1973). Voice-timing perception in Spanish word-initial stops. Journal of Phonetics, 1, 1-18. Abramson, A. & Lisker, L. (1967). Discriminability along the voicing continuum: Cross language tests. Proceedings of the Sixth International Congress of Phonetic Sciences, Prague, pp. 569-573. Prague: Academia. ·· Bond, Z. S., Eddey, J. & Bermejo, J. (1980) . VOT del Espaii.ol to English: Comparison of!anguagedisordered and normal child. Journal of Phonetics, 8, 287-291. Eimas, P. (1975). Speech perception in early infancy. In Infant Perception: From Sensation to Cognition. Vol. II (L. Cohen and P. Salapatek eds), pp. 193-231. New York: Academic Press. Kewly-Port, D. & Preston, M. (1974). Early apical stop production: A voice onset time analysis. Journal of Phonetics, 2, 195-210. Lisker, L. & Abramson, A. (1964). A cross-language study of voicing in initial stops; Acoustical measurements. Word, 20, 384--422. Lisker, L. & Abramson, A. (1971). Distinctive features and laryngeal control. Language, 4 7, 770. Menyuk, P. & Looney, P. (1972). Relationships among components of the grammar in language disorders. Journal of Speech and Hearing Research, 15, 395-406. Moffitt, A. (1971). Consonant cue perception by twenty to twenty-four week old infants. Child Development,42, 717-731. Morse, P. (1972). The discrimination of speech and nonspeech stimuli in early infancy. Journal of Experimental Child Psychology , 14,477-492. Panagos, J. (1974). Persistance of the open syllable reinterpreted as a symptom of a language disorder. Journal of Speech and Hearing Research, 39, 23-31. Preston, M., Yeni-Komshian, G. & Stark, R. (1967). Voicing in initial stop consonants produced by children in the prelinguistic period from different language communities. Johns Hopkins University School of Medicine, Annual Report of Neurocommunications Laboratory, 2, 305-323.
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Trehub, S. & Rabinovitch, M. (1972). Auditory-linguistic sensitivity in early infancy. Developmental Psychology, 6, 74-77. Zlatin, M. & Koenigsknecht, R. (1976). Development of the voicing contrast. A comparison of voice onset time values in stop perception and production. Journal of Speech and Hearing Research, 19, 93- 111. Zlatin, M. & Koenigsknecht, R. (1975). Development of the voicing contrast: perception of stop consonants. Journal of Speech and Hearing Research, 18,541-553.