What Can a Child Do With One Normal-Hearing Ear? Speech Perception and Word Learning in Children With Unilateral and Bilateral Hearing Losses Relative to Peers With Normal Hearing.

OBJECTIVES: To examine the effects of unilateral hearing loss on children's ability to perceive familiar words and to learn and retain new words. Because children with unilateral hearing loss receive full auditory input in one ear, their performance was expected to be consistent with that of children with normal hearing rather than that of children with moderate bilateral hearing loss. DESIGN: Participants were 36 school-age children with normal hearing bilaterally, 11 children with moderate bilateral hearing loss, and 11 children with mild-to-profound unilateral hearing loss (six right and five left). Half of the normally hearing children and two-thirds of the children with unilateral hearing loss were from bilingual Spanish/English-speaking homes. One of the 11 children with bilateral hearing loss was from a bilingual Spanish/English-speaking home. All children completed a word recognition test in English and in Spanish, a word-learning task comprised of nonsense words constructed using the phonotactic rules of English, Spanish, and Arabic, and a next-day word-retention test. RESULTS: Word recognition did not differ across groups in English or Spanish. Learning and retention of nonsense words was highest for the children with normal hearing in all three languages. The children with unilateral and bilateral losses learned and recalled the English nonsense words as well as their normally hearing peers, but performance for the Spanish and Arabic nonsense words was significantly and similarly reduced by hearing loss in either ear. CONCLUSIONS: Failure to learn and retain new words given a full auditory representation in one ear suggests that children with unilateral and bilateral hearing losses may share a unifying feature of impairment at the level of the central auditory system.

Bone Conduction Amplification in Children: Stimulation via a Percutaneous Abutment versus a Transcutaneous Softband.

OBJECTIVES: Research suggests that the speech perception of children using bone conduction amplification improves if the device is coupled to an implanted abutment rather than to a softband. The purpose of the present study was to determine if the benefit of direct stimulation via an abutment is limited to small improvements in speech perception or if similar or greater benefits occur for other auditory tasks important for learning and communication. DESIGN: Fourteen children (7 to 15 years of age) with bilateral conductive and three children with unilateral conductive or sensorineural hearing loss were enrolled. Each child completed four tasks while using a bone conduction device coupled to an implanted abutment and with the device coupled to a softband. The two devices were worn at the same time and activated one at a time for testing. The children completed four tasks under each coupling condition: (a) a traditional word recognition task, (b) an auditory lexical decision task in which the children repeated aloud, and indicated the category of, real and nonsense words, (c) a nonsense-word detection task which required the children to identify nonsense words within short sentences, and (d) a rapid word learning task in which the children learned to associate nonsense words with novel images. RESULTS: Regression analyses revealed that age, duration of device use, in-situ hearing thresholds, or device output did not account for a significant portion of the variability in performance for any of the four tasks. Repeated-measures analysis of variance revealed significant increases in word recognition with the abutment as well as significantly better performance for the lexical decision and word learning tasks. The data indicated that the children with the poorest performance with the softband tended to benefit most with the abutment. Also, the younger children showed improved performance for more tasks with the abutment than the older children. No difference between coupling conditions was observed for nonsense-word detection. CONCLUSIONS: The improved recognition of familiar words, categorization and repetition of nonsense words, and speed of word learning with the abutment suggests that direct stimulation provides a higher-quality signal than indirect stimulation through a softband. Because these processes are important for vocabulary acquisition and language development, children may experience long-term benefits of direct stimulation for academic, social, and vocational purposes in addition to immediate improvement in communication.

Auditory Lexical Decision and Repetition in Children: Effects of Acoustic and Lexical Constraints.

OBJECTIVES: The objective of this study was to identify factors that may detract from children's ability to identify words they do and do not know. Factors investigated were acoustic constraints stemming from the presence of hearing loss (HL) or an acoustic competitor, and lexical constraints due to an impoverished or cluttered vocabulary. DESIGN: Eleven children with normal hearing (NH) and 11 children with bilateral, mild to moderately severe sensorineural HL were asked to categorize and repeat two-syllable real and nonsense words. Stimuli were amplified and frequency shaped for each child with HL and presented randomly at a level consistent with average conversational speech (65 dB SPL). About half of the children in each group listened in quiet while the other half listened in multitalker babble. In addition to overall performance, responses were judged based on the word category chosen by the child (real or nonsense), the category of the word produced by the child as judged by an examiner (real or nonsense), and the accuracy of the verbal response compared with the stimulus. From these judgments, 10 discrete types of errors were identified. Analyses were conducted for three different combinations of the 10 error categories to best characterize the effects of acoustic and lexical constraints. RESULTS: Performance was highest for real words presented in quiet and poorest for nonsense words presented in multitalker babble. Also, the performance of the children with HL was poorer than that of the children with NH. Error analyses revealed strong effects of acoustic constraints on performance but few effects of lexical constraints. The two most frequently occurring errors were the same for both children with NH and the children with HL and entailed the misperception of nonsense words and the mistaking of nonsense words for real words. However, while both groups of children exhibited these errors in multitalker babble, the children with HL demonstrated these errors in quiet as well. CONCLUSIONS: These results suggest that children's interactions with real and nonsense words are significantly constrained when the acoustic signal is degraded by HL and/or an acoustic competitor. The children's tendency to repair unknown words into real words in the presence of acoustic interference may be beneficial when perceiving familiar speech, but could also be detrimental if that tendency causes them to miss opportunities to learn new words.

Cav1.2 and Cav1.3 L-type calcium channels regulate dopaminergic firing activity in the mouse ventral tegmental area.

Dopaminergic projections from the ventral tegmental area (VTA) constitute the mesolimbocortical system that underlies addiction and psychosis primarily as a result of increased dopaminergic transmission. Dopamine release is spike dependent. L-type calcium channels (LTCCs) play an important role in regulating firing activities, but the contribution of specific subtypes remains unclear. This article describes different functions of Cav1.2 and Cav1.3 subtypes in regulating firing properties with two transgenic mouse strains. For basal firing, Cav1.3-deficient (Cav1.3(-/-)) mice had a lower basal firing frequency. The dihydropyridine (DHP) channel blocker nifedipine reduced single-spike firing in mice expressing DHP-insensitive Cav1.2 channels (Cav1.2DHP(-/-) mice), confirming the significant contribution from the Cav1.3 subtype in basal firing. Moreover, the DHP channel activator (S)-(-)-Bay K8644 and the non-DHP channel activator FPL 64176 converted firing patterns from single spiking to bursting in Cav1.2DHP(-/-) mice. Nifedipine inhibited burst firing induced by both activators, suggesting that Cav1.3 also serves an essential role in burst firing. However, FPL 64176 also induced bursting in Cav1.3(-/-) mice. These results indicate that the Cav1.3 subtype is crucial to regulation of basal single-spike firing, while activation of both Cav1.2 and Cav1.3 can support burst firing of VTA neurons.

Spatial Hearing in Children With and Without Hearing Loss: Where and What the Speech Is Matters for Local Speech Intelligibility.

PURPOSE: This study examined children's ability to perceive speech from multiple locations on the horizontal plane. Children with hearing loss were compared to normal-hearing peers while using amplification with and without advanced noise management. METHOD: Participants were 21 children with normal hearing (9-15 years) and 12 children with moderate symmetrical hearing loss (11-15 years). Word recognition, nonword detection, and word recall were assessed. Stimuli were presented randomly from multiple discrete locations in multitalker noise. Children with hearing loss were fit with devices having separate omnidirectional and noise management programs. The noise management feature is designed to preserve audibility in noise by rapidly analyzing input from all locations and reducing the noise management when speech is detected from locations around the hearing aid user. RESULTS: Significant effects of left/right and front/back lateralization occurred as well as effects of hearing loss and hearing aid noise management. Children with normal hearing experienced a left-side advantage for word recognition and a right-side advantage for nonword detection. Children with hearing loss demonstrated poorer performance overall on all tasks with better word recognition from the back, and word recall from the right, in the omnidirectional condition. With noise management, performance improved from the front compared to the back for all three tasks and from the right for word recognition and word recall. CONCLUSIONS: The shape of children's local speech intelligibility on the horizontal plane is not omnidirectional. It is task dependent and shaped further by hearing loss and hearing aid signal processing. Front/back shifts in children with hearing loss are consistent with the behavior of hearing aid noise management, while the right-side biases observed in both groups are consistent with the effects of specialized speech processing in the left hemisphere of the brain.

Effects of semantic and acoustic context on nonword detection in children with hearing loss.

PURPOSE: Children with hearing loss (HL) are known to have smaller receptive vocabularies than children with normal hearing (NH). This may be due, in part, of their reduced exposure to new words and their slower rate of word learning. A necessary prerequisite to lexical development is the detection of new words in conversation. The purpose of this study was to examine the effects of HL on children's ability to detect the presence of nonwords within sentences that varied in semantic and acoustic context. METHODS: Twenty-nine children with NH and 16 children with HL between the ages of 7 and 13 years participated. The children listened to short sentences and reported the number of nonwords detected, ranging from zero to two nonwords, in each sentence. The structure of the sentences was either meaningful or nonsensical to the children to reveal the effects of semantic context. The effects of acoustic context were revealed by presenting the sentences in quiet, steady-state noise, and in multi-talker babble. RESULTS: Significant effects of age (older > younger), hearing (NH > HL), and listening condition (quiet > noise and babble) were observed. Also, nonword detection was better for semantically meaningful sentences than for nonsense sentences. Error analyses revealed that the children with NH tended to underestimate the number of nonwords in meaningful sentences but not in nonsense sentences. The children with HL, however, were more likely to underestimate the number of nonwords than were the children with NH for both meaningful and nonsense sentences. These error patterns were observed in each listening condition. CONCLUSIONS: Error patterns suggest that children with HL apply strong repair strategies during speech perception, which may limit their opportunities to learn new words.

Task-Dependent Effects of Signal Audibility for Processing Speech: Comparing Performance With NAL-NL2 and DSL v5 Hearing Aid Prescriptions at Threshold and at Suprathreshold Levels in 9- to 17-Year-Olds With Hearing Loss.

Hearing aid fitting formulas intended for the pediatric population can differ by 6 to 25 dB in prescribed output across frequency leading to large variations in aided audibility. Children perceive these differences and have expressed preferences that favor more audibility for quiet speech and less audibility for noisy speech. In this study, the effect of variations in audibility consistent with hearing aid fittings for children was examined. Sixteen children and adolescents (9-17 years) with mild-to-moderate hearing loss participated. Hearing aids programed to National Acoustic Laboratories or Desired Sensation Level v5.0a targets were fitted to each participant. Also, separate programs with and without a low-level adaptive gain feature were provided with each prescription. Speech reception threshold (SRT) was measured as well as performance for four suprathreshold auditory tasks that increased in cognitive demand. These tasks were word recognition, nonword detection, multiword recall, and rapid word learning. A significant effect of fitting formula, but not low-level or adaptive gain, was observed for SRT. Significant effects of presentation level, fitting formula, and low-level gain were observed for word recognition. The effect of presentation level was significant for nonword detection, multiword recall, and rapid word learning but no other main effects or interactions were significant. Finally, word recognition and nonword detection increased significantly with audibility while multiword recall and word learning did not. The results suggest that audibility assists with the initial perception of auditory input but plays a smaller role in memory formation and learning.

Sentence perception in listening conditions having similar speech intelligibility indices.

OBJECTIVE: The objective of this study was to examine the relation between bandwidth and speech perception in normally hearing adults and children at a single value of the Speech Intelligibility Index (SII). DESIGN: The SII of meaningful and nonsense sentences were held constant for each of three bandwidths to test the hypothesis that perception would be equivalent in each condition. The sentences were filtered to produce three bandwidth conditions (low-pass cut-off frequency: 0.8, 1.25, 2.5 kHz) and the sensation level within each bandwidth was adjusted to produce a similar SII (0.43-0.48). Sentences were presented in broadband noise to facilitate equivalent audibility across subjects in each bandwidth condition. STUDY SAMPLE: Participants were 20 adults between the ages of 19 and 47 years and 20 eight-year-old children. All participants had normal hearing. RESULTS AND CONCLUSION: Contrary to the hypothesis, performance of both groups increased significantly as bandwidth increased. Significant main effects of group and sentence type were also found. These results indicate that performance was governed largely by the bandwidth of the stimuli and that those effects were not represented well in the SII.

Learning and Retention of Novel Words in Musicians and Nonmusicians.

Purpose The purpose of this study was to determine whether long-term musical training enhances the ability to perceive and learn new auditory information. Listeners with extensive musical experience were expected to detect, learn, and retain novel words more effectively than participants without musical training. Advantages of musical training were expected to be greater for words learned in multitalker babble compared to quiet. Method Participants consisted of 20 young adult musicians and 20 age-matched nonmusicians, all with normal hearing. In addition to completing word recognition and nonword detection tasks, each participant learned 10 novel words in a rapid word-learning paradigm. All tasks were completed in quiet and in multitalker babble. Next-day retention of the learned words was examined in isolation (recall) and in the context of continuous discourse (detection). Performance was compared across groups and listening conditions. Results Performance was significantly poorer in babble than in quiet on word recognition and nonword detection, but not on word learning, learned-word recall, or learned-word detection. No differences were observed between groups (musicians vs. nonmusicians) on any of the tasks. Conclusions For young normal-hearing adults, auditory experience resulting from long-term music training did not enhance their learning of new auditory information in either favorable (quiet) or unfavorable (babble) listening conditions. This suggests that the formation of semantic and musical representations in memory may be supported by the same underlying auditory processes, such that musical training is simply an extension of an auditory expertise that both musicians and nonmusicians possess.

Is Oral Bilingualism an Advantage for Word Learning in Children With Hearing Loss?

Purpose The purpose of this study was to examine whether oral bilingualism could be an advantage for children with hearing loss when learning new words. Method Twenty monolingual and 13 bilingual children with hearing loss were compared with each other and with 20 monolingual and 20 bilingual children with normal hearing on receptive vocabulary and on three word-learning tasks containing nonsense words in familiar (English and Spanish) and unfamiliar (Arabic) languages. We measured word learning on the day of the training and retention the next day using an auditory recognition task. Analyses of covariance were used to compare performance on the word learning tasks by language group (monolingual vs. bilingual) and hearing status (normal hearing vs. hearing loss), controlling for age and maternal education. Results No significant differences were observed between monolingual and bilingual children with and without hearing loss in any of the word-learning task. Children with hearing loss performed more poorly than their hearing peers in Spanish word retention and Arabic word learning and retention. Conclusions Children with hearing loss who grew up being exposed to Spanish did not show higher or lower word-learning abilities than monolingual children with hearing loss exposed to English only. Therefore, oral bilingualism was neither an advantage nor a disadvantage for word learning. Hearing loss negatively affected performance in monolingual and bilingual children when learning words in languages other than English (the dominant language). Monolingual and bilingual children with hearing loss are equally at risk for word-learning difficulties and vocabulary size matters for word learning.

Immediate and long-term effects of hearing loss on the speech perception of children.

The purpose of the present study was to examine the immediate and long-term effects of hearing loss on the speech perception of children. Hearing loss was simulated in normally-hearing children and their performance was compared to that of children with hearing loss (long-term effects) as well as to their own performance in quiet (immediate effects). Eleven children with normal hearing (7-10 years) were matched to five children with mild to moderate sensorineural hearing loss (8-10 years). Frequency-shaped broadband noise was used to elevate the hearing thresholds of the children with normal hearing to those of their matched hearing-impaired peer. Meaningful and nonsense sentences were presented at five levels and quantified using an audibility index (AI). Comparison of the AI functions calculated for each group and listening condition revealed a significant, immediate effect of elevated hearing thresholds in the children with normal hearing but no long-term effects of hearing loss. The results of this study suggest that hearing loss affects speech perception adversely and that amplification does not fully compensate for those effects. However, the data suggest that over the long term children may develop compensatory strategies to reduce the effects of hearing loss.

Use of forward pressure level to minimize the influence of acoustic standing waves during probe-microphone hearing-aid verification.

Probe-microphone measurements are a reliable method of verifying hearing-aid sound pressure level (SPL) in the ear canal for frequencies between 0.25 and 4 kHz. However, standing waves in the ear canal reduce the accuracy of these measurements above 4 kHz. Recent data suggest that speech information at frequencies up to 10 kHz may enhance speech perception, particularly for children. Incident and reflected components of a stimulus in the ear canal can be separated, allowing the use of forward (incident) pressure as a measure of stimulus level. Two experiments were conducted to determine if hearing-aid output in forward pressure provides valid estimates of in-situ sound level in the ear canal. In experiment 1, SPL measurements were obtained at the tympanic membrane and the medial end of an earmold in ten adults. While within-subject test-retest reliability was acceptable, measures near the tympanic membrane reduced the influence of standing waves for two of the ten participants. In experiment 2, forward pressure measurements were found to be unaffected by standing waves in the ear canal for frequencies up to 10 kHz. Implications for clinical assessment of amplification are discussed.

Perceptual coherence in listeners having longstanding childhood hearing losses, listeners with adult-onset hearing losses, and listeners with normal hearing.

Perceptual coherence, the process by which the individual elements of complex sounds are bound together, was examined in adult listeners with longstanding childhood hearing losses, listeners with adult-onset hearing losses, and listeners with normal hearing. It was hypothesized that perceptual coherence would vary in strength between the groups due to their substantial differences in hearing history. Bisyllabic words produced by three talkers as well as comodulated three-tone complexes served as stimuli. In the first task, the second formant of each word was isolated and presented for recognition. In the second task, an isolated formant was paired with an intact word and listeners indicated whether or not the isolated second formant was a component of the intact word. In the third task, the middle component of the three-tone complex was presented in the same manner. For the speech stimuli, results indicate normal perceptual coherence in the listeners with adult-onset hearing loss but significantly weaker coherence in the listeners with childhood hearing losses. No differences were observed across groups for the nonspeech stimuli. These results suggest that perceptual coherence is relatively unaffected by hearing loss acquired during adulthood but appears to be impaired when hearing loss is present in early childhood.

Short-term word-learning rate in children with normal hearing and children with hearing loss in limited and extended high-frequency bandwidths.

PURPOSE: This study examined children's word learning in limited and extended high-frequency bandwidth conditions. These conditions represent typical listening environments for children with hearing loss (HL) and children with normal hearing (NH), respectively. METHOD: Thirty-six children with NH and 14 children with moderate-to-severe HL served as participants. All of the children were between 8 and 10 years of age and were assigned to either the limited or the extended bandwidth conditions. Five nonsense words were paired with 5 novel pictures. Word learning was assessed in a single session, multitrial, learning paradigm lasting approximately 15 min. Learning rate was defined as the number of exposures necessary to achieve 70% correct performance. RESULTS: Analysis of variance revealed a significant main effect for bandwidth but not for group. A Bandwidth x Group interaction was also not observed. In this short-term learning paradigm, the children in both groups required 3 times as many exposures to learn each new word in the limited bandwidth condition compared with the extended bandwidth condition. CONCLUSION: These results suggest that children with HL may benefit from extended high-frequency amplification when learning new words and for other long-term auditory processes.

Effect of minimal hearing loss on children's ability to multitask in quiet and in noise.

PURPOSE: The purpose of the present study was to examine the effect of minimal hearing loss (HL) on children's ability to perform simultaneous tasks in quiet and in noise. METHOD: Ten children with minimal HL and 11 children with normal hearing (NH) participated. Both groups ranged in age from 8 to 12 years. The children categorized common words (primary task) while completing dot-to-dot games (secondary task) in quiet as well as in noise presented at 0 dB and +6 dB signal-to-noise ratios (SNRs). It was hypothesized that the children's progression through the dot-to-dot games would slow as they encountered more difficult listening environments. This hypothesis was based on the theory that listeners have limited cognitive resources to allocate to any combination of tasks. RESULTS: The dot rate of both groups decreased similarly in the multitasking conditions relative to baseline. However, no other differences between groups or listening conditions were revealed. Significantly poorer word categorization was observed for the children with minimal HL in noise. CONCLUSION: These data suggest that children with minimal HL may be unable to respond to a difficult listening task by drawing resources from other tasks to compensate.

Vocal Biomarkers of Mild-to-Moderate Hearing Loss in Children and Adults: Voiceless Sibilants.

Purpose: The purpose of this study was to determine if an objective measure of speech production could serve as a vocal biomarker for the effects of high-frequency hearing loss on speech perception. It was hypothesized that production of voiceless sibilants is governed sufficiently by auditory feedback that high-frequency hearing loss results in subtle but significant shifts in the spectral characteristics of these sibilants. Method: Sibilant production was examined in individuals with mild to moderately severe congenital (22 children; 8-17 years old) and acquired (23 adults; 55-80 years old) hearing losses. Measures of hearing level (pure-tone average thresholds at 4 and 8 kHz), speech perception (detection of nonsense words within sentences), and speech production (spectral center of gravity [COG] for /s/ and /ʃ/) were obtained in unaided and aided conditions. Results: For both children and adults, detection of nonsense words increased significantly as hearing thresholds improved. Spectral COG for /ʃ/ was unaffected by hearing loss in both listening conditions, whereas the spectral COG for /s/ significantly decreased as high-frequency hearing loss increased. The distance in spectral COG between /s/ and /ʃ/ decreased significantly with increasing hearing level. COG distance significantly predicted nonsense-word detection in children but not in adults. Conclusions: At least one aspect of speech production (voiceless sibilants) is measurably affected by high-frequency hearing loss and is related to speech perception in children. Speech production did not predict speech perception in adults, suggesting a more complex relationship between auditory feedback and feedforward mechanisms with age. Even so, these results suggest that this vocal biomarker may be useful for identifying the presence of high-frequency hearing loss in adults and children and for predicting the impact of hearing loss in children.

Development of an instrument to evaluate audiologic counseling skills.

This study describes the development of an instrument designed to evaluate audiologic counseling skills. In simulated counseling sessions, a trained actor portrayed a parent, and ten graduate audiology students role-played counseling sessions as audiologists informing the "parent" that her infant has a hearing loss. The ten sessions were videotaped, and three raters viewed the taped sessions while evaluating counseling skills with a new evaluation tool, the Audiologic Counseling Evaluation (ACE). The ACE was found to have excellent internal reliability (alpha = .91) and moderate-to-good inter-rater reliability. Raters' subjective evaluations of the tool were generally positive, and students' evaluations of the simulated counseling experience were overwhelmingly so. This instrument can be used by audiology faculty and clinical instructors to help students improve their counseling skills before interacting with parents. It can also be used in clinical settings for professional development by way of self- and peer-evaluation.

Word Recognition and Learning: Effects of Hearing Loss and Amplification Feature.

Two amplification features were examined using auditory tasks that varied in stimulus familiarity. It was expected that the benefits of certain amplification features would increase as the familiarity with the stimuli decreased. A total of 20 children and 15 adults with normal hearing as well as 21 children and 17 adults with mild to severe hearing loss participated. Three models of ear-level devices were selected based on the quality of the high-frequency amplification or the digital noise reduction (DNR) they provided. The devices were fitted to each participant and used during testing only. Participants completed three tasks: (a) word recognition, (b) repetition and lexical decision of real and nonsense words, and (c) novel word learning. Performance improved significantly with amplification for both the children and the adults with hearing loss. Performance improved further with wideband amplification for the children more than for the adults. In steady-state noise and multitalker babble, performance decreased for both groups with little to no benefit from amplification or from the use of DNR. When compared with the listeners with normal hearing, significantly poorer performance was observed for both the children and adults with hearing loss on all tasks with few exceptions. Finally, analysis of across-task performance confirmed the hypothesis that benefit increased as the familiarity of the stimuli decreased for wideband amplification but not for DNR. However, users who prefer DNR for listening comfort are not likely to jeopardize their ability to detect and learn new information when using this feature.

Detecting and Learning New Words: The Impact of Advancing Age and Hearing Loss.

PURPOSE: Lexical acquisition was examined in children and adults to determine if the skills needed to detect and learn new words are retained in the adult years. In addition to advancing age, the effects of hearing loss were also examined. METHOD: Measures of word recognition, detection of nonsense words within sentences, and novel word learning were obtained in quiet for 20 children with normal hearing and 21 with hearing loss (8-12 years) as well as for 15 adults with normal hearing and 17 with hearing loss (58-79 years). Listeners with hearing loss were tested with and without high-frequency acoustic energy to identify the type of amplification (narrowband, wideband, or frequency lowering) that yielded optimal performance. RESULTS: No differences were observed between the adults and children with normal hearing except for the adults' better nonsense word detection. The poorest performance was observed for the listeners with hearing loss in the unaided condition. Performance improved significantly with amplification to levels at or near that of their counterparts with normal hearing. With amplification, the adults performed as well as the children on all tasks except for word recognition. CONCLUSIONS: Adults retain the skills necessary for lexical acquisition regardless of hearing status. However, uncorrected hearing loss nearly eliminates these skills.

The importance of high-frequency audibility in the speech and language development of children with hearing loss.

OBJECTIVES: To review recent research studies concerning the importance of high-frequency amplification for speech perception in adults and children with hearing loss and to provide preliminary data on the phonological development of normal-hearing and hearing-impaired infants. DESIGN AND SETTING: With the exception of preliminary data from a longitudinal study of phonological development, all of the reviewed studies were taken from the archival literature. To determine the course of phonological development in the first 4 years of life, the following 3 groups of children were recruited: 20 normal-hearing children, 12 hearing-impaired children identified and aided up to 12 months of age (early-ID group), and 4 hearing-impaired children identified after 12 months of age (late-ID group). Children were videotaped in 30-minute sessions at 6- to 8-week intervals from 4 to 36 months of age (or shortly after identification of hearing loss) and at 2- and 6-month intervals thereafter. Broad transcription of child vocalizations, babble, and words was conducted using the International Phonetic Alphabet. A phoneme was judged acquired if it was produced 3 times in a 30-minute session. SUBJECTS: Preliminary data are presented from the 20 normal-hearing children, 3 children from the early-ID group, and 2 children from the late-ID group. RESULTS: Compared with the normal-hearing group, the 3 children from the early-ID group showed marked delays in the acquisition of all phonemes. The delay was shortest for vowels and longest for fricatives. Delays for the 2 children from the late-ID group were substantially longer. CONCLUSIONS: The reviewed studies and preliminary results from our longitudinal study suggest that (1) hearing-aid studies with adult subjects should not be used to predict speech and language performance in infants and young children; (2) the bandwidth of current behind-the-ear hearing aids is inadequate to accurately represent the high-frequency sounds of speech, particularly for female speakers; and (3) preliminary data on phonological development in infants with hearing loss suggest that the greatest delays occur for fricatives, consistent with predictions based on hearing-aid bandwidth.