Hearing Speakers Research Articles

Bilingual/Bicultural Deaf Education: An Overview

Methods and approaches used to foster English language acquisition in deaf students have a long history of change. The recent use of manually coded English (MCE) systems has not produced desired results. Current research on American Sign Language (ASL) has proved it to be a genuine language with its own systems for making words and sentences. The acceptance of ASL has led to increased demands that deaf students be allowed to acquire ASL as a first language and English as a second language. Proposed methods for teaching English as a second language have been drawn from models of second language acquisition in hearing speakers. Because language and culture are closely related, these proposed bilingual ASL/English models include a cultural as well as a linguistic component. Several proposed models and related research are here examined and a pilot program for bilingual/ bicultural teaching is suggested.

Perseveratory Coarticulation in the Speech of Profoundly Hearing-Impaired and Normally Hearing Children

This study investigated the extent of perseveratory coarticulation in the VC syllables [i integral of, u integral of, it, ut, ik, uk] as produced by 7- and 10-year-old normally hearing and profoundly hearing-impaired children. Measures of both temporal and spectral (centroid and F2 frequency) parameters were computed. The data revealed that the hearing-impaired speakers exhibited measurable but smaller effects of perseveratory coarticulation relative to the normally hearing speakers. These results are compared with studies of anticipatory coarticulation and are discussed in relation to the claim that perseveratory coarticulation is largely a result of the inertial properties of the speech production mechanism.

Accent and Intonation of Speech in Adolescents with Severe and Profound Hearing Impairments

The purpose of the present study was to analyze the characteristics of the speech of adolescents with severe and profound hearing impairments. This formed part of a broad study on accent and intonation in adolescents with severe and profound hearing impairments. The test words consisted of two-mora words in which the first or second mora is high-pitched. Parameters of acoustic analysis were fundamental frequency and intensity. Samples were recorded and analyzed by Phono-Laryngograph (RION SH-01) in experiment 1 and Digital Sona-Graph (KAY7800) in experiment 2. From the results of this study the following findings were observed.The hearing impaired speakers realized accent in the following ways : (1) increase in intensity in the first mora of the test word, (2) increase in pitch in the second mora of the test word. The movements of pitch contour in normal hearing speakers were dynamic. In adolescents with severe and profound hearing impairments, dynamics were lower than in the normal speakers. For intonations, pitch movements at the end of utterances were examined. Word-final pitch rise occurred in normal speakers, but did not occur in adolescents with severe and profound hearing impairments.

The influence of final-syllable position on the vowel and word duration of deaf talkers.

Hearing talkers produce shorter vowel and word durations in multisyllabic contexts than in monosyllabic contexts. This investigation determined whether a similar effect occurs for deaf talkers, a population often characterized as lacking coarticulation in their speech. Four prelingually deafened adults and two hearing controls produced three sets of word sequences. Each set included a kernel word and six derived forms (e.g., "speed," "speedy," "speeding," etc.). The derived forms were created by adding unstressed and stressed syllables to the kernel form. A spectrographic analysis indicated that the deaf subjects did not always decrease word and vowel durations for the derivatives. Unlike hearing speakers, they often did not reduce vowel segments more than consonant segments. Three explanations are forwarded for the shortening effects. One relates to the implementation of temporal rules, the second concerns the organization imposed upon the articulators to produce speech, and the third suggests a language-independent vocal tract characteristic. The role of auditory information in developing the shortening effects is also considered.

Vowel durational characteristics daring simultaneous communication

The purpose of this investigation was to study vowel durations during speech produced simultaneously with sign language and fingerspelling and to determine whether final consonant influences on vowel durations, which occur naturally in speech, also occur in speech produced during simultaneous communication. Vowel durations were obtained for the vowels /ɑ/, /ɪ/, and /æ/, which were embedded in CVC words in which the final consonant was systematically varied. All CVCs met the criteria of having a common sign and of being phonetically and orthographically correlated. The CVCs were embedded in a carrier phrase and were uttered by ten normally hearing speakers fluent in sign language, under conditions of: speech, speech combined with sign language, and speech combined with signing of the carrier phrase and fingerspelling of the CVC. Results indicated that vowels produced with accompanying sign language and fingerspelling were significantly longer in duration than those produced during speech alone. Further, it was found that in both the signed and fingerspelled conditions, as in speech alone, vowels followed by a voiced consonant were longer in duration than vowels followed by their voiceless cognate.

Children's understanding of referential messages produced by deaf and hearing speakers

Children 4 to 10 years of age were presented with referential messages that varied in message adequacy and speech quality and were required to choose the intended referent from a set of four alternatives. Follow ing feedback regarding their choice, they evaluated the message as good or bad and provided reasons for their evaluation. Half of the messages had sufficient information to define the referent uniquely; half had insufficient or ambiguous information. Moreover, half of the messages were produced by hearing children and half by deaf children. Children's comprehension and evaluation of messages changed sys tematically with age, as did the basis for these evaluations. The 4- and 5-year-olds performed poorly on the picture selection task but evaluated most messages as good; 6-year-olds rated messages as good if they had chosen the correct referent, even by guessing. From 8 years of age, children judged the adequacy of messages independent of outcome and linked their justifications to relevant details of the mes sages. Messages that were fully intelligible to adults but had atypical speech quality resulted in poorer performance and evaluations than did messages with normal speech quality for children of all ages.

Laryngeal kinematics in voiceless obstruents produced by hearing-impaired speakers.

During normal production of voiceless consonants several events occur simultaneously in the vocal tract. These events must be temporally coordinated. Earlier work has indicated that a breakdown in interarticulator timing can contribute to the characteristic voiced-voiceless errors produced by hearing-impaired speakers. The present study examines kinematic details of the laryngeal articulatory gesture in 2 deaf speakers and a control subject using transillumination of the larynx. Results indicate that hearing-impaired speakers often do not produce differences between stops and fricatives in the kinematic details of the gesture. That is to say, although hearing speakers commonly use a larger laryngeal gesture for fricatives than for stops and also show durational differences of the abduction and the adduction phases between phonetic categories, the hearing-impaired subjects did not make them. Also, the deaf speakers participating in this study were more variable in the kinematic measures.

Stress contrast perception by the hearing impaired: Auditory, tactile, auditory‐tactile

The perception of stress contrasts in deaf subjects was assessed under three conditions—auditory only, tactile only, and combined auditory‐tactile. Test stimuli were three disyllables generated in a two‐stage process: multiple repetitions of each disyllable were produced by a normally hearing speaker using normal or exaggerated stress on either the first or second syllable; the averaged acoustic values for peak amplitude, vowel duration, and peak fundamental frequency for each disyllable were then resynthesized and manipulated to create a stimulus set containing none, one, two, and three of the acoustic cues denoting stress. Subjects were asked to indicate whether stress occurred on the first or second syllable for each stimulus item. Performance was above the level of chance in all three conditions. In the exaggerated stress production mode, performance in the tactile condition exceeded performance in the auditory condition for those stimulus items containing a frequency cue. [Work supported by ♯NS‐17764.]

Effects of vowel context on the articulatory closure postures of deaf speakers.

Using cinefluorography, this investigation evaluated how the bilabial and dorsal stop closure postures of 2 hearing and 5 deaf speakers varied with vowel context. The jaw and tongue body postures of the hearing and the 2 most intelligible deaf speakers altered with the identity of the following vowel. This did not occur consistently for the remaining deaf speakers. The results concur with a previous suggestion (Tye, Zimmerman, & Kelso, 1983) that some speakers who learn speech without audition may develop a different articulatory coordination than hearing speakers. Discovering these differences may lead to a general account for many of their intelligibility deficits.

Jaw kinematics in hearing-impaired speakers

This study examines jaw movements as a function of vowel height and stress in real-word phrases produced by three hearing-impaired speakers and a hearing control. Movements of the lips and jaw were recorded using an optical tracking system. Measures included duration, displacement, and peak velocity of movement. There were statistically significant main effects for vowel height in nearly all movement records for both the hearing-impaired and the hearing speakers. However, the related measures for stress had no significant effects for the subjects. The hearing speaker distinguished stressed and unstressed segments by maintaining the jaw in a lowered position for a longer period in the stressed vowels. With few exceptions, kinematic values for the hearing and the hearing-impaired speakers were comparable. These results thus suggest that some characteristics of speech production are not adversely affected by congenital and profound hearing loss. [Work supported by NIH.]

Lip‐jaw coordination in hearing‐impaired speakers

The question posed is whether interarticulator timing relationships are preserved in deaf speakers across speech transformations such as those induced by phonetic context and stress. Acoustic recordings were obtained simultaneously with kinematic records of lip and jaw motions using the Selspot infrared tracking device. The experimental corpus included real word utterances with a medial labial consonant (p,b,m,w,f,v) flanked by one high and one low vowel (e.g., “And Bea pops it”). The stimuli were produced by one hearing and three hearing‐impaired talkers. Measures of jaw and lip displacement and velocity of movement were made in order to address questions of kinematics as a function of stress, phonetics, and vowel effects. Results for the hearing speaker showed the expected systematic differentiation of stressed and unstressed syllables. Preliminary results for the hearing‐impaired speakers showed the relative interarticulator timing was more variable than the normal. However, the deaf speakers were like normal in that they differentiated vowels on the basis of jaw placement. These and other measures to investigate phonetic effects will be presented. [Work supported by NIH Grants NS‐13617 and NS‐13870.]

The effect of segmental and suprasegmental corrections on the intelligibility of deaf speech

Three experiments were conducted to study the effect of segmental and suprasegmental corrections on the intelligibility and judged quality of deaf speech. By means of digital signal processing techniques, including LPC analysis, transformations of separate speech sounds, temporal structure, and intonation were carried out on 30 Dutch sentences spoken by ten deaf children. The transformed sentences were tested for intelligibility and acceptability by presenting them to inexperienced listeners. In experiment 1, LPC based reflection coefficients describing segmental characteristics of deaf speakers were replaced by those of hearing speakers. A complete segmental correction caused a dramatic increase in intelligibility from 24% to 72%, which, for a major part, was due to correction of vowels. Experiment 2 revealed that correction of temporal structure and intonation caused only a small improvement from 24% to about 34%. Combination of segmental and suprasegmental corrections yielded almost perfectly understandable sentences, due to a more than additive effect of the two corrections. Quality judgments, collected in experiment 3, were in close agreement with the intelligibility measures. The results show that, in order for these speakers to become more intelligible, improving their articulation is more important than improving their production of temporal structure and intonation.

Development of sign-based perception by deaf children.

In this study the sign-based perceptual abilities of 59 deaf children are investigated. Like many hearing speaking children, deaf signing children appear to perceive isolated lexical items based on the formational parameters of those items. Also, deaf signers show trends similar to those exhibited by hearing speakers for the development of the perceptual ability necessary to distinguish between minimal pairs within their respective language systems.

Do the effects of adventitious deafness include disordered speech?

The popular clinical prediction is that adventitious deafness will result in deterioration of speech sound production; consequently, a recommendation of speech conservation training is thought to be warranted in these cases. This prediction usually follows from a theory that counts feedback (particularly auditory feedback) as important in the maintenance of normal speech. The results of this study, designed to examine the speech of five adventitiously deafened adults matched with a group of normal controls, do not support the prediction of speech deterioration. Even so, judges were able to differentiate deafened from normally hearing speakers. Some possibilities are considered that could account for the identity of the deafened speakers in the absence of clinically significant speech disorder, and clinicians are encouraged to reevaluate their assumptions concerning this population.

Airflow characteristics of fricative consonants produced by normally hearing and hearing-impaired speakers.

The purpose of this study was to investigate the rates of airflow for fricative consonants produced by normally hearing speakers and by hearing-impaired speakers who varied in degree of hearing loss and speech intelligibility. Subjects consisted of 20 normally hearing adults (10 men and 10 women), 20 moderately-to-severely hearing-impaired adults with intelligible speech (10 men and 10 women), and 20 profoundly hearing-impaired adults with semi-intelligible speech (10 men and 10 women). Average airflow rates were obtained for the fricatives /s/, /z/, /f/, and /v/ in CV and VCV syllables. In general, it was found that normally hearing, intelligible hearing-impaired, and some semi-intelligible hearing-impaired speakers produced voiceless fricatives with substantially greater airflow rates than they produced voiced cognates. The data also revealed that both male and female semi-intelligible hearing-impaired speakers produced fricatives in the CV context with greater amounts of airflow and fricatives in the VCV environment with less airflow than did the normally hearing and intelligible hearing-impaired speakers. Further, the male and female semi-intelligible hearing-impaired speakers failed to demonstrate the trend, as exhibited by the other speakers, for lingua-alveolar fricatives to be produced with greater air flow than the labiodental fricatives. The data from this investigation provide additional evidence to support the assumption that some hearing-impaired speakers fail to control and coordinate the biomechanical aspects of speech properly.

“Compensatory articulation” in hearing impaired speakers: a cinefluorographic study

Data from three hearing-impaired subjects were compared with data from three hearing subjects to study the effect of constraining the jaw during speech on tongue shape and position for the vowels /i/, /æ/ and /u/. The results showed that although the three hearing-impaired speakers showed more variable tongue shapes and positions in both bite-block and nonbite-block conditions, the bite-block had little effect in altering the areas of maximum constriction between the tongue dorsum and maxilla associated with the vowels studied. Two of the hearing-impaired speakers showed less differentiation in tongue shape and position for the vowels /u/ and /æ/ in both jaw-fixed and jaw-free conditions. A third hearing-impaired speaker differentiated the vowels but the tongue positions observed were different from those of normal hearing speakers. The bite-block was shown to have no systematic effect on intelligibility for any of the hearing-impaired speakers. These findings are interpreted in terms of current thinking on sensorimotor integration and movement control with particular reference to “target-based” theories.

Obstruent production by hearing-impaired speakers: interarticulator timing and acoustics.

This study examines the organization of laryngeal control and interarticulator timing in the production of obstruents and obstruent clusters by three severely-profoundly deaf adults. Glottal activity was monitored by transillumination; temporal patterns of oral articulation (lips and tongue-palate) were recorded using an electrical transconductance technique. For each of the deaf speakers, an inappropriate abduction gesture was often found between words, a pattern never observed for hearing speakers. At the same time, the deaf speakers differed from each other with respect to types of errors, variability, and interarticulator coordination. For the most intelligible speaker, the timing of glottal opening with respect to oral articulation was most like that observed for normals. The second deaf speaker often failed to observe voicing contrasts with respect to glottal opening. This subject was nevertheless consistent in producing most plosives without a glottal opening, and all fricatives with an opening gesture. For the third deaf speaker, the pattern of errors was more complex and included both missing and inappropriate glottal opening gestures.

The mechanics of abnormal laryngeal devoicing gestures exhibited by deaf persons

High-speed laryngeal films were obtained from one normally hearing and four deaf subjects as they produced /ihi/ syllables. Computer assisted frame-by-frame analysis indicated that during /h/ productions the deaf subjects frequently achieved glottal areas that were three times greater than the normally hearing speakers'. These findings are consistent with previously reported data [Metz and Whitehead, J. Acoust. Soc. Am. Suppl. 1 68, S114 (1980)]. Additionally, glottal area changes over time associated with the normally hearing subjects' /h/ productions appear to be continuous in nature. Vocal fold abductory movement away from V1 was virtually contiguous with the adductory movement toward V2. In contrast, glottal area changes over time associated with many of the deaf subjects' /h/ productions appear to be discontinuous in nature. Such area changes were characterized by abrupt vocal fold abductory movements away from V1 and plateaus in the area change. The temporal nature of this motion suggests that each segment of the syllable was produced discreetly on a phoneme-by-phoneme basis. Issues regarding speech air stream economy and speech motor control in the deaf will be addressed. [Work supported by the U.S. Department of Education.]

Laryngeal‐oral coordination in the production of obstruents by hearing impaired speakers

The study examines the organization of laryngeal control and inter‐articulator timing in the production of voiceless obstruents by hearing impaired speakers. Three severe‐profoundly deaf adults served as subjects. Laryngeal activity was monitored by trans‐illumination; temporal patterns of oral articulation (lips and tongue‐palate) were recorded using an electrical transconductance technique. For each of the deaf speakers, an inappropriate abduction gesture immediately preceded production of the test word, a pattern never observed for hearing speakers. However, the deaf speakers differed from each other with respect to type of errors, variability, and interarticulator coordination. For the more intelligible deaf speaker, the timing of glottal opening with respect to oral articulation was most like that observed for normals. The second deaf speaker often failed to observe voicing contrasts with respect to glottal opening; that is, he failed to produce an opening gesture for voiceless obstruents as normals. For the third deaf speaker, the pattern of errors appears to be more complex including both missing and inappropriate glottal opening gestures. Data will be discussed with respect to listener judgments. [Work supported by NINCDS and BRSG.]

Some aerodynamic characteristics of plosive consonants produced by hearing-impaired speakers.

The purpose of this study was to investigate the rate of oral air flow for plosive consonants produced by 10 normal hearing adult males, 10 hearing-impaired adult males who demonstrated intelligible speech, and 10 hearing-impaired adult males with semi-intelligible speech. The peak rate of oral air flow was measured during production of CV and VCV syllables consisting of the vowels /a/ and /i/ and the consonants /b/, /p/, /d/, and /t/. In general, the results indicated that a significant voiced/voiceless distinction, for rate of air flow, occurred for the normally hearing and intelligible hearing-impaired subjects but not for the semi-intelligible subjects. In addition, the semi-intelligible hearing impaired, in the CV context, produced voiced plosives with significantly greater air flow and voiceless plosives with significantly less air flow; and, produced both voiced and voiceless plosives, in the VCV context, with significantly less air flow, when compared with the normally hearing and intelligible hearing-impaired speakers.