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Tongue shape can vary greatly for allophones of /r/ produced in different phonetic contexts but the primary acoustic cue used by listeners, lowered F3, remains stable. For the current study, it was hypothesized that auditory feedback maintains the speech motor control mechanisms that are constraining acoustic variability of F3 in /r/; thus the listener’s percept remains /r/ despite the range of articulatory configurations employed by the speaker. Given the potential importance of auditory feedback, postlingually deafened speakers should show larger acoustic variation in /r/ allophones than hearing controls, and auditory feedback from a cochlear implant could reduce that variation over time. To test these hypotheses, measures were made of phoneme perception and of production of tokens containing /r/, stop consonants, and /r/+stop clusters in hearing controls and in eight postlingually deafened adults pre- and postimplant. Postimplant, seven of the eight implant speakers did not differ from the control mean. It was also found that implant users’ production of stop and stop+/r/ blend improved with time but the measured acoustic contrast between these was still better in the control speakers than for the implant group even after the implant users had experienced a year of improved auditory feedback.

Purpose To describe cochlear implant users' phoneme labeling, discrimination, and prototypes for a vowel and a sibilant contrast, and to assess the effects of 1 year’s experience with prosthetic hearing. Method Based on naturally produced clear examples of “boot,” “beet,” “said,” and “shed” by 1 male and 1 female speaker, continua with 13 stimuli were synthesized for each contrast. Seven hearing controls labeled those stimuli and assigned them goodness ratings, as did 7 implant users at 1-month postimplant. One year later, these measures were repeated, and within category discrimination, d ′, was assessed. Results Compared with controls, implant users' vowel and sibilant labeling slopes were substantially shallower but improved over 1 year of prosthesis use. Their sensitivity to phonetic differences within phoneme categories was about half that of controls. The slopes of their goodness rating functions were shallower and did not improve. Their prototypes for the sibilant contrast (but not the vowels) were closer to one another and did not improve by moving apart. Conclusions Implant users' phoneme labeling and within-category perceptual structure were anomalous at 1-month postimplant. After 1 year of prosthesis use, phoneme labeling categories had sharpened but within category discrimination was well below that of hearing controls.

The question of why some individuals make progress in speech therapy while others do not remains largely unanswered. Treatment delivery method could be a factor; individuals whose speech sounds have not improved through traditional therapy may be more responsive to alternative forms of treatment, such as visual biofeedback. The present study utilized visual biofeedback in the form of Opti-Speech, which uses real-time, three-dimensional streaming data from the Wave EMA system to create an avatar of a participant’s tongue. Participants included two adult females with residual /r/ errors. One participant demonstrated marked improvement during and after treatment, while the other exhibited little perceptual change. It is possible that a more flexible motor system (i.e., one that shows more variability as a new skill is being learned) is more conducive to the acquisition of new speech sound movements than a more rigid system. Kinematic data were analyzed from each session, including duration, maximum displacem...

Objective: This study investigates the role of hearing in vowel productions of postlingually deafened cochlear implant users. Two hypotheses are tested that derive from the view that vowel production is influenced by competing demands of intelligibility for the listener and least effort in the speaker: 1) Hearing enables a cochlear implant user to produce vowels distinctly from one another; without hearing, the speaker may give more weight to economy of effort, leading to reduced vowel separation. 2) Speakers may need to produce vowels more distinctly from one another in a language with a relatively crowded vowel space, such as American English, than in a language with relatively few vowels, such as Spanish. Thus, when switching between hearing and non-hearing states, English speakers may show a tradeoff between vowel distinctiveness and least effort, whereas Spanish speakers may not. Design: To test the prediction that there will be a reduction of average vowel spacing (AVS) (average intervowel distance in the F1-F2 plane) with interrupted hearing for English-speaking cochlear implant users, but no systematic change in AVS for Spanish cochlear implant users, vowel productions of seven English-speaking and seven Spanish-speaking cochlear implant users, who had been using their implants for at least 1 yr, were recorded when their implant speech processors were turned off and on several times in two sessions. Results: AVS was consistently larger for the English speakers with hearing than without hearing. The magnitude and direction of AVS change was more variable for the Spanish speakers, both within and between subjects. Conclusion: Vowel distinctiveness was enhanced with the provision of some hearing in the language group with a more crowded vowel space but not in the language group with fewer vowels. The view that speakers seek to minimize effort while maintaining the distinctiveness of acoustic goals receives some support.

This study investigates covariation of perception and production of vowel contrasts in speakers who use cochlear implants and identification of those contrasts by listeners with normal hearing. Formant measures were made of seven vowel pairs whose members are neighboring in acoustic space. The vowels were produced in carrier phrases by 8 postlingually deafened adults, before and after they received their cochlear implants (CI). Improvements in a speaker's production and perception of a given vowel contrast and normally hearing listeners' identification of that contrast in masking noise tended to occur together. Specifically, speakers who produced vowel pairs with reduced contrast in the pre-CI condition (measured by separation in the acoustic vowel space) and who showed improvement in their perception of these contrasts post-CI (measured with a phoneme identification test) were found to have enhanced production contrasts post-CI in many cases. These enhanced production contrasts were associated, in turn, with enhanced masked word recognition, as measured from responses of a group of 10 normally hearing listeners. The results support the view that restoring self-hearing allows a speaker to adjust articulatory routines to ensure sufficient perceptual contrast for listeners.

According to a dual-process theory of the role of hearing in speech production, hearing helps maintain an internal model used by the speech control mechanism to achieve phonemic goals. It also monitors the acoustic environment and guides relatively rapid adjustments in postural parameters, such as those underlying average speech sound level and rate, in order to achieve suprasegmental goals that are a compromise between intelligibility and economy of effort. In order to obtain evidence bearing on this theory, acoustic and aerodynamic measures were collected from seven adventitiously deaf speakers who received cochlear implants, three speakers who had severe reduction in hearing following surgery for Neurofibromatosis-2, and one hard of hearing speaker. These speakers made recordings of the Rainbow Passage and an English vowel inventory before and after intervention. All but one of the postlingually deaf speakers who received prosthetic hearing reduced speech sound level, SPL. Three of these significantly increased a measure of inferred glottal aperture, H1-H2, and their session means for these two parameters were inversely correlated longitudinally. All but one of the speakers terminated respiratory limbs closer to functional residual capacity (FRC) once prosthetic hearing was supplied. Finally, the implant users' average values of air expenditure moved toward normative values with prosthetic hearing. These results are attributed to the mediation of changes in respiratory and glottal posture aimed at reducing speech sound level and economizing effort.

PurposeThe authors sought to describe longitudinal changes in Percentage of Consonants Correct—Revised (PCC–R) after severe pediatric traumatic brain injury (TBI), to compare the odds of normal-range PCC–R in children injured at older and younger ages, and to correlate predictor variables and PCC–R outcomes.MethodIn 56 children injured between age 1 month and 11 years, PCC–R was calculated over 12 monthly sessions beginning when the child produced ≥ 10 words. At each session, the authors compared odds of normal-range PCC–R in children injured at younger (≤ 60 months) and older (> 60 months) ages. Correlations were calculated between final PCC–R and age at injury, injury mechanism, gender, maternal education, residence, treatment, Glasgow Coma Score, and intact brain volume.ResultsPCC–Rs varied within and between children. Odds of normal-range PCC–R were significantly higher for the older than for the younger group at all sessions but the first; odds of normal-range PCC–R were 9 to 33 times higher in the older group in sessions 3 to 12. Age at injury was significantly correlated with final PCC–R.ConclusionOver a 12-month period, severe TBI had more adverse effects for children whose ages placed them in the most intensive phase of PCC–R development than for children injured later.

Visual biofeedback, commonly delivered by a display of ultrasound of tongue position, has demonstrated effectiveness for treating residual speech errors in older children and adults. It can be challenging to make kinematic measures during treatment without the use of a head stabilizing system, however, and it is likewise not possible to measure the changes in speech motor control that accompany improvements in speech sound production. Opti-Speech, a visual biofeedback treatment software that uses EMA to provide positional data, has the benefit of providing a steady stream of position data throughout baseline and treatment sessions. In this study, Opti-Speech treatment was provided with an intensive schedule (2x/day for 5 days) to two adolescent males with persistent speech errors (i.e., lateralized /s/). Marked improvements in /s/ accuracy and quality were noted over the course of treatment and are reported in another paper (Mental et al., this meeting). Kinematic measures were made of tongue position thr...

An age-related increase in the fricative contrast /s/-/ʃ/, measured acoustically, occurs in children up to 7 years of age, with 5- and 7-year-olds producing contrasts that are greater than those of younger children, but still significantly smaller than the contrasts produced by adults. Kinematic studies have demonstrated that adult-like speech motor control does not emerge until later adolescence, although no articulatory studies of sibilant production in later childhood have been reported. In this study, the aim was to understand the relative use of somatosensory and acoustic/auditory goals for the production of the fricative contrast in older children (10–15 years of age) and adults. The fricative contrast was measured in the acoustic signal and in articulatory data gathered from the tongue blade. The acoustic and articulatory contrasts were analyzed to test the magnitude of the covariation of the two domains. We further analyzed the development of the contrast in both domains as a function of later speech development. Results will be discussed in the context of the hypothesis that sibilants are produced with prominent goals in both the somatosensory and auditory domains but that auditory goals predominate in older children because of continued refinement of feedforward commands.

PurposeTo assess the effects of short- and long-term changes in auditory feedback on vowel and sibilant contrasts and to evaluate hypotheses arising from a model of speech motor planning.MethodThe perception and production of vowel and sibilant contrasts were measured in 8 postlingually deafened adults prior to activation of their cochlear implant speech processors, 1 month postactivation, and 1 year postactivation. Measures were taken postactivation both with and without auditory feedback. Contrast measures were also made for a group of speakers with reportedly normal hearing speaking with masked and unmasked auditory feedback.ResultsVowel and sibilant contrasts, measured in the absence of auditory feedback after 1 month of prosthesis use, were diminished compared with their values measured before prosthesis. Contrasts measured in the absence of auditory feedback after 1 year’s experience with the prosthesis were increased compared with their values after 1 month’s experience. In both time samples, contrasts were enhanced when auditory feedback was restored.ConclusionThe provision of prosthetic hearing to postlingually deafened adults impaired their phonemic contrasts at first, as their auditory feedback had novel characteristics. Once auditory feedback became recalibrated with prosthesis use, it could, in turn, revise feedforward commands that control the contrasts in its absence.

The timing of changes in parameters of speech production was investigated in six cochlear implant users by switching their implant microphones off and on a number of times in a single experimental session. The subjects repeated four short, two-word utterances, /dV1n#SV2d/ (S = /s/ or /S/), in quasi-random order. The changes between hearing and nonhearing states were introduced by a voice-activated switch at V1 onset. "Postural" measures were made of vowel sound pressure level (SPL), duration, F0; contrast measures were made of vowel separation (distance between pair members in the formant plane) and sibilant separation (difference in spectral means). Changes in parameter values were averaged over multiple utterances, lined up with respect to the switch. No matter whether prosthetic hearing was blocked or restored, contrast measures for vowels and sibilants did not change systematically. Some changes in duration, SPL and F0 were observed during the vowel within which hearing state was changed, V1, as well as during V2 and subsequent utterance repetitions. Thus, sound segment contrasts appear to be controlled differently from the postural parameters of speaking rate and average SPL and F0. These findings are interpreted in terms of the function of hypothesized feedback and feedforward mechanisms for speech motor control.

The role of auditory feedback in speech production was investigated by examining speakers’ phonemic contrasts produced under increases in the noise to signal ratio (N/S). Seven cochlear implant users and seven normal-hearing controls pronounced utterances containing the vowels /i/, /u/, /e/ and /ae/ and the sibilants /s/ and /ʃ/ while hearing their speech mixed with noise at seven equally spaced levels between their thresholds of detection and discomfort. Speakers’ average vowel duration and SPL generally rose with increasing N/S. Average vowel contrast was initially flat or rising; at higher N/S levels, it fell. A contrast increase is interpreted as reflecting speakers’ attempts to maintain clarity under degraded acoustic transmission conditions. As N/S increased, speakers could detect the extent of their phonemic contrasts less effectively, and the competing influence of economy of effort led to contrast decrements. The sibilant contrast was more vulnerable to noise; it decreased over the entire range of increasing N/S for controls and was variable for implant users. The results are interpreted as reflecting the combined influences of a clarity constraint, economy of effort and the effect of masking on achieving auditory phonemic goals—with implant users less able to increase contrasts in noise than controls.

This study explores the effects of hearing status and bite blocks on vowel production. Normal-hearing controls and postlingually deaf adults read elicitation lists of ∕hVd∕ syllables with and without bite blocks and auditory feedback. Deaf participants’ auditory feedback was provided by a cochlear prosthesis and interrupted by switching off their implant microphones. Recording sessions were held before prosthesis was provided and one month and one year after. Long-term absence of auditory feedback was associated with heightened dispersion of vowel tokens, which was inflated further by inserting bite blocks. The restoration of some hearing with prosthesis reduced dispersion. Deaf speakers’ vowel spaces were reduced in size compared to controls. Insertion of bite blocks reduced them further because of the speakers’ incomplete compensation. A year of prosthesis use increased vowel contrast with feedback during elicitation. These findings support the inference that models of speech production must assign a role to auditory feedback in error-based correction of feedforward commands for subsequent articulatory gestures.

Objective This study examines changes in the intelligibility of CVC words spoken by postlingually deafened adults after they have had 6 to 12 mo of experience with a cochlear implant. The hypothesis guiding the research is that the intelligibility of these speakers will improve after extended use of a cochlear implant. The paper also describes changes in CVC word intelligibility analyzed by phoneme class and by features. Design The speech of eight postlingually deaf adults was recorded before activation of the speech processors of their cochlear implants and at 6 mo and 1 yr after activation. Seventeen listeners with no known impairment of hearing completed a word identification task while listening to each implant user’s speech in noise. The percent information transmitted by the speakers in their pre- and postactivation recordings was measured for 11 English consonants and eight vowels separately. Results An overall improvement in word intelligibility was observed: seven of the eight speakers showed improvement in vowel intelligibility and six speakers showed improvement in consonant intelligibility. However, the intelligibility of specific consonant and vowel features varied greatly across speakers. Conclusions Extended use of a cochlear implant by postlingually deafened adults tends to enhance their intelligibility.

In order to examine the role of hearing status in controlling coarticulation, eight English vowels in /bVt/ and /dVt/ syllables, embedded in a carrier phrase, were elicited from 7 postlingually deafened adults and 2 speakers with normal hearing. The deaf adults served in repeated recording sessions both before and up to a year after they received cochlear implants and their speech processors were turned on. Each of the two hearing control speakers served in two recording sessions, separated by about 3 months. Measures were made of second formant frequency at obstruent release and at 25 ms intervals until the final obstruent. An index of coarticulation, based on the ratio of F2 at vowel onset to F2 at midvowel target, was computed. Changes in the amount of coarticulation after the change in hearing status were small and nonsystematic for the /bVt/ syllables; those for the /dVt/ syllables averaged a 3% increase—within the range of reliability measures for the 2 hearing control speakers. Locus equations (F2 at vowel onset vs. F2 at vowel midpoint) and ratios of F2 onsets in point vowels were also calculated. Like the index of coarticulation, these measures tended to confirm that hearing status had little if any effect on coarticulation in the deaf speakers, consistent with the hypothesis that hearing does not play a direct role in regulating anticipatory coarticulation in adulthood. With the restoration of some hearing, 2 implant users significantly increased the average spacing between vowels in the formant plane, whereas the remaining 5 decreased that measure. All speakers but one also reduced vowel duration significantly. Four of the speakers reduced dispersion of vowel formant values around vowel midpoint means, but the other 3 did not show this effect.

This study examined the relationship between acoustic correlates of stress in trochaic (strong‐weak), spondaic (strong‐strong), and iambic (weak‐strong) nonword bisyllables produced by children (3;0‐5;0) with normal speech acquisition and children with speech delay. Ratios comparing the acoustic measures (vowel duration, rms, and f0) of the first syllable to the second syllable were calculated to evaluate the extent to which each phonetic parameter was used to mark stress. In addition, a calculation of the variability of jaw movement in each bisyllable was made. Finally, perceptual judgments of accuracy of stress production were made. Analysis of perceptual judgments indicated a robust difference between groups: While both groups of children produced errors in imitating the contrastive lexical stress models (∼40%), the children with normal speech acquisition tended to produce trochaic forms in substitution for other stress types, whereas children with speech delay showed no preference for trochees. The relationship between segmental acoustic parameters, kinematic variability, and the ratings of stress by trained listeners will be presented.

This study investigates the role of hearing in vowel productions of postlingually deafened cochlear implant (CI) users. Based on the hypothesis that competing demands of intelligibility and economy of effort influence vowel production, we predicted that speakers of a language with a more crowded vowel space, such as American English, would show an increase in average vowel spacing (AVS the average inter‐vowel distance in the F1‐F2 plane) with the provision of hearing from a CI; whereas speakers of a language with fewer vowels, such as Spanish, would not. Results of a preliminary on–off study supported the hypothesis: with hearing from a CI, 7 English‐speaking CI users all increased AVS; however, among 7 Spanish speakers, some increased AVS and some reduced it. The current study is exploring these findings further with new groups of CI users and normal‐hearing speakers of English and Spanish and an elaborated paradigm that includes different speaking rates and comparisons between pre‐implant and post‐impla...

This study investigates relations among speech perception, speech production, and intelligibility in postlingually deaf adults who receive cochlear implants (CI). Measures were made for seven vowel pairs that neighbor in acoustic space from eight postlingually deafened adults, pre‐ and postimplant. Improvements in a speaker’s production, perception, and intelligibility of a given vowel contrast tended to occur together. Subjects who produced vowel pairs with reduced contrast in the preimplant condition (measured by separation in the acoustic vowel space) and who showed improvement in their perception of these contrasts postimplant (measured with a phoneme identification test) were found to have improved production contrasts post‐CI. These enhanced production contrasts were associated with enhanced intelligibility, as measured from responses of a group of normal‐hearing listeners. The results support the hypothesis that the implant user’s improving speech perception contributes, at least in part, to that speaker’s improving speech production. [Work supported by the NIDCD, NIH.]

This investigation explored whether meaningful subgroups of children would emerge from a heterogeneous population of typical preschool speakers as a result of convergences of measures from multiple speech production subsystems: behavioral, phonatory, articulatory, and respiratory. Because variability is a ubiquitous characteristic of preschool speech production, the goal of this classification was not only to minimize within‐subgroup variability, but to identify the latent parameters across speech subsystems that characterized each resulting subgroup with the goal of better understanding the refinement of speech motor control that takes place at this stage of development. It is critical to understand the range of performance and interactions among speech production subsystems that exist in children with typical speech development so that we can better quantify the deviancies observed in children with speech disorders. Data were gathered from 60 speakers, aged 37–59 months, and analyzed using multivariate pattern‐based classification analyses. The result was two distinct clusters of individuals whose performance across speech subsystems was differentiated by stability. One group was characterized by higher levels of variability across phonatory, articulatory, and respiratory subsystems compared to the second group. The groups did not differ significantly by composition in terms of age or sex.

This study investigates the effects of speaking condition and auditory feedback on vowel production by postlingually deafened adults. Thirteen cochlear implant users produced repetitions of nine American English vowels prior to implantation, and at one month and one year after implantation. There were three speaking conditions (clear, normal, and fast), and two feedback conditions after implantation (implant processor turned on and off). Ten normal-hearing controls were also recorded once. Vowel contrasts in the formant space (expressed in mels) were larger in the clear than in the fast condition, both for controls and for implant users at all three time samples. Implant users also produced differences in duration between clear and fast conditions that were in the range of those obtained from the controls. In agreement with prior work, the implant users had contrast values lower than did the controls. The implant users' contrasts were larger with hearing on than off and improved from one month to one year postimplant. Because the controls and implant users responded similarly to a change in speaking condition, it is inferred that auditory feedback, although demonstrably important for maintaining normative values of vowel contrasts, is not needed to maintain the distinctiveness of those contrasts in different speaking conditions.

As part of a large‐scale study that aims to create a data‐driven model of speech delay of unknown origin (SD) in preschool children, this investigation analyzed two‐ and three‐syllable nonword repetitions by 50 3‐ to 5‐year‐old children, half of whom are typically developing (TD). The syllable repetition task was composed of four different words, bama, bada, bamana, and manaba, selected both for articulatory simplicity and to maximize displacement of the external articulators for kinematic analyses. While children in the TD group were significantly more accurate in both two‐ and three‐syllable repetitions than children in the SD group, neither group was able to repeat three‐syllable nonwords with particular acumen. Children in the TD group were 55% accurate, while children in the SD group were only 22% accurate. Measures of repetition accuracy, acoustics, nasalence, external articulatory kinematics, and respiration contribute to a hierarchical agglomerative clustering model that generates hypotheses about potential subclinical categories within the SD and TD groups.

This study investigates the effects of speaking condition and hearing status on vowel production by postlingually deafened adults. Thirteen cochlear implant users produced repetitions of nine American English vowels in three time samples (prior to implantation, one month, and one year after implantation); in three speaking conditions (clear, normal, and fast); and in two feedback conditions after implantation (implant processor turned on and off). Ten speakers with normal hearing were also recorded. Results show that vowel contrast, in the F1 versus F2 space, in mels, does not differ from the pre‐implant stage to the 1‐month stage. This finding indicates that shortly after implantation, speakers had not had enough experience with hearing from the implant to adequately retune their auditory feedback systems and use auditory feedback to improve feedforward commands. After 1 year of implant use, contrast distances had increased in both feedback conditions (processor on and off), indicating improvement in feedforward commands for phoneme production. Furthermore, after long‐term auditory deprivation, speakers were producing differences in contrast between clear and fast conditions in the range of those found for normal‐hearing speakers, leading to the inference that maintenance of these distinctions is not affected by hearing status. [Research supported by NIDCD.]

This study was designed to evaluate the control of jaw movement in contrastive stress productions of children with and without speech delay. The spatiotemporal index (STI) was used to calculate variability in jaw movement trajectories in 12 children producing three different metrical forms of CVCV syllables (trochaic, iambic, and even stress; papa, mama, and baba). The children (mean age: 3;2 years) were categorized, four in each of three groups, as having Normal Speech Acquisition (NSA), Speech Delay (SD), or both (NSA/SD) using the Speech Disorder Classification System (Shriberg et al., 1997). Results replicated findings in typically developing children of a similar age reported by Goffman and Malin (1999) where iambic forms were produced with greater stability than trochaic forms as measured by the STI. Analysis using a repeated measures ANOVA revealed significant effects for contrastive stress type, speech disorder classification, and syllable identity. Results are reported in the context of vowel aco...

This study examined the effect on the vowel contrast distance (average inter‐vowel distance in the F1−F2 plane) of gradually decreasing the signal‐to‐noise ratio (SNR) in the auditory feedback of a post‐lingually deafened cochlear implant (CI) user at 1‐month and 1‐year following CI processor activation. Masking noise, mixed with normal levels of speech feedback, was presented through the headpiece of a research sound processor to the CI user. As a control, an analogous procedure was used for a normal‐hearing speaker where the masking noise and speech feedback were delivered over headphones. The SNR was gradually decreased over seven steps as the speakers produced ten repetitions of two vowel contrasts (ae\/[g\/] and i\/u). Speech SPL and vowel contrast distance were measured at all seven masking noise levels. Data from both subjects showed that SPL gradually increased with decreased SNR, while contrast distance decreased. The effect was greater after 1 year of experience with a CI than at 1 month. The effect in the NH speaker was similar to that noted in the CI user after 1 year of experience. Data from additional subjects will be analyzed and reported. [Work supported by NIH Grant No. R01 DC03007.]

This study explores the effect of hearing status on adaptation to a bite block in vowel productions of normal hearing (NH) adults and adults who use cochlear implants (CI). CI speakers are tested prior to and following experience with the implant. Different sized bite blocks (BB) are used to create unusual degrees of mandibular opening for vowel productions in an /hVd/ context (had, head, heed, hid, and hod). Four conditions are elicited from each NH and CI speaker: (1) no BB with hearing (CI processor on), (2) no BB with no hearing (NH speakers with masking noise and CI speakers with processor off), (3) BB with no hearing, and (4) BB with hearing. Prior to fitting with the implant, CI speakers are tested without hearing in two conditions: (1) no BB and (2) BB. Spectra of the vowel productions are analyzed for dispersion of tokens in the F1–F2 plane in the four conditions. Pilot results support the hypothesis that prior to fitting, CI users are less able to adapt to perturbations than NH speakers and that...

In listeners with normal hearing, the sight of a speaker’s face articulating a syllable can influence the auditory percept, most observably when the auditory and visual stimuli are different from one another. This study investigates differences in audio‐visual (AV) integration (‘‘the McGurk effect’’) between adults with hearing loss who wear hearing aids (HA) and their normal‐hearing (NH) counterparts. The following hypothesis is being tested: HA users will rely more on visual input and thus be biased more toward the visual stimulus in the mismatch condition. Audio‐visual stimuli from three speakers are presented, pairing the consonants /b/, /d/, and /g/ with the vowels /a/, /i/, and /u/, in three conditions (auditory‐only, visual‐only, and AV) to the two subject groups, NH and HA. Participants label each stimulus according to the consonant perceived. Responses are coded into four categories: fusion, combination, auditory, or visual. Data analysis examines the relative strength of visual influences in the two groups. Pilot data show fusion and visual bias in an HA user. Further results will be presented. [Work supported by NIH.]

To investigate the speed of speech production changes in response to a change in hearing, the speech processors of two cochlear implant users were switched on and off a number of times in a single experimental session for each subject. The subjects repeated short utterances (‘‘a said,’’ ‘‘a shed,’’ ‘‘a sad,’’ and ‘‘a shad’’) many times in semi‐random order. The transitions between hearing (on) and nonhearing (off) states were timed to occur between utterances, and the number of utterances between transitions was varied to minimize subject anticipation of the change. Using transition times as line‐up points, values of median and skewness of sibilant spectra and vowel F1, F2, duration, and SPL were each averaged over repetitions of each utterance and compared across the on–off and off–on transitions. Vowel SPL and duration had changed by the first utterance following the transition, indicating that the subjects were using subtle aspects of the processor output to detect its state even in the absence of overt sound input. Changes in spectral median and skewness and F1 and F2 were less immediate, more varied, and differed between the two subjects. The paradigm is currently being refined to further investigate this issue. [Work supported by NIH.]