Management of hearing loss in infants: the UTD/Callier Center position statement.

As infants are being identified earlier and earlier by universal newborn hearing screening programs, there is a need to establish principles for professionals involved in habilitative processes. Recently, a panel of experts was convened for a 2-day conference entitled "Habilitative Issues for Infants with Hearing Loss," the Bruton Conference on Audiology/Communication Sciences, UTD/Callier Center for Communication Disorders. The purpose of this document was to summarize the panel's discussions on habilitative principles, state-of-the-art practices, and future needs for infants with hearing loss.

Developmental course of auditory processing interactions: Garner interference and Simon interference.

Previous research suggests that with increasing age children become more efficient in inhibiting conflicting responses and in resisting interference from irrelevant information. We assessed the abilities of 100 children (ages 3-16 years) and 20 adults to resist interference during the processing of 2 auditory dimensions of speech, namely the speaker's gender and spatial location. The degree of interference from irrelevant variability in either dimension did not vary with age. Apparently, young children do not have more difficulty in resisting interference when the nontarget and the target are both perceptual attributes. We also assessed the participants' abilities to inhibit conflicting task-irrelevant information from spatial location and to resist interference from spatial variability in the context of conflict. In the presence of conflicting task-irrelevant information, both interference effects declined significantly with age. Developmental change in auditory processing seems to vary as a function of (1) the nature of the target-nontarget combination and (2) the presence/absence of conflicting task-irrelevant information.

Electrophysiologic indices of Stroop and Garner interference reveal linguistic influences on auditory and visual processing.

The purpose of this study was to examine linguistic influences on the auditory and visual processing of words both behaviorally and electrophysiologically. Our task yielded measures of the effect of irrelevant semantic content (Stroop interference) and of the effect of irrelevant linguistic variability (Garner interference). The behavioral results allow us to assess whether the linguistic and nonlinguistic dimensions of verbal stimuli are processed dependently or independently. The electrophysiologic results allow us to determine where any processing interactions are arising, particularly regarding perceptual versus postperceptual underpinnings, and to evaluate the similarity and dissimilarity between the two interference effects. Results show pronounced Stroop and Garner interference both behaviorally and electrophysiologically, indicating linguistic influences on auditory and visual processing. Subjects could not ignore the irrelevant linguistic dimension and attend selectively to the physical dimension of either spoken or written words. The results indicate that the physical and linguistic dimensions of words are not processed independently. With regard to the stage of processing underlying the interference effects, our results suggest that both Stroop and Garner interference involve multiple stages of processing. The two interference effects are not duplicate measures, however, and different electrophysiologic signatures were observed. Stroop interference is characterized by perceptual and postperceptual components. Similar electrophysiologic patterns within the auditory and visual modalities suggest that each interference effect is tapping similar processes for spoken and written stimuli.

Childhood hearing impairment: processing dependencies in multidimensional speech perception for an auditory level of analysis.

OBJECTIVE: Our purpose was to determine whether the influence of childhood hearing impairment (HI) on multidimensional speech processing is a purely linguistic effect or whether childhood HI also affects the processing of speech dimensions representing an auditory level of analysis. DESIGN: The processing dependencies characterizing the two dimensions of talker-gender and spatial location were studied in 40 children with HI and in two normal-hearing (NH) comparison groups representing similar chronological ages (N = 30) or similar vocabulary skills (N = 70). The processing interactions were assessed with a speeded selective-attention task requiring listeners to attend selectively to the gender of the talker and to ignore the spatial location and vice versa. The logic is that performance for the target dimension will not be affected by what is happening on the nontarget dimension if the dimensions are processed independently. On the other hand, if the dimensions are not processed independently, listeners will not be able to attend selectively and performance for the relevant dimension will be affected by what is happening on the irrelevant dimension. In the latter case, results may be analyzed in terms of Garner interference (the effect on performance of irrelevant variability in the to-be-ignored dimension) (Garner, 1974a) and Simon interference (the effect on performance of an irrelevant spatial source) (Simon, 1990). RESULTS: Overall results in all listeners, those with NH or HI, showed significant interference when the participants were attending to the gender of the talker and ignoring spatial location and vice versa. The talker-gender and spatial-location dimensions of speech were not processed independently by these children. When the processing interactions were compared between the NH and HI groups, the presence of childhood HI as a general rule significantly diminished the degree of interference from spatial location. The degree of interference from the gender of the talker, on the other hand, remained normal in the presence of childhood HI. All listeners seemed stimulus bound by the gender of the talker. The degree of Garner interference did not show age-related or degree of loss-related change. The degree of Simon interference showed significant change as a function of age in the children with mild-moderate HI, but not in the children with severe HI. The developmental function for Simon interference in the children with mild-moderate HI was delayed to a degree that corresponded to the duration of the auditory deprivation. CONCLUSIONS: The overall pattern of results indicates that the influence of childhood HI on multidimensional speech processing is not a purely linguistic effect.

Childhood hearing impairment: auditory and linguistic interactions during multidimensional speech processing.

Children with mild-severe sensorineural hearing losses often use hearing aids and aural/oral language as their primary mode of communication, yet we know little about how speech is processed by these children. The purpose of this research was to investigate how the multidimensional information underlying accurate speech perception is processed by children with mild-severe hearing impairments. The processing of the auditory and linguistic dimensions of speech was assessed with a speeded selective-attention task (Garner, 1974a). Listeners were required to attend selectively to an auditory dimension (gender of the talker) and ignore a linguistic dimension (word) and vice versa. The hypothesis underlying the task is that performance for the target dimension will be unaffected by what is happening on the nontarget dimension if the dimensions are processed independently. On the other hand, if the dimensions are not processed independently, listeners will not be able to attend selectively and performance for the relevant dimension will be affected by what is happening on the irrelevant dimension (termed "Garner" interference). Both children with normal hearing (N = 90) and children with hearing impairment (N = 40) showed some degree of Garner interference, implying that the dimensions of speech are not processed independently by these children. However, relative to the children with normal hearing, the children with hearing impairment showed normal Garner interference when attending selectively to the word dimension (normally effective at ignoring talker-gender input) and reduced Garner interference when attending selectively to the talker-gender dimension (more effective at ignoring word input). This pattern of results implies that the auditory dimension has a normal strength-of-processing level that makes it normally distracting and that the linguistic dimension has an underdeveloped strength-of-processing level that makes it easier to ignore in children with hearing impairment.

Linguistic influences on the auditory processing of speech by children with normal hearing or hearing impairment.

OBJECTIVE: The accurate perception of speech requires the processing of multidimensional information. The aim of this research was to examine linguistic influences on the auditory processing of speech in the presence of childhood hearing impairment. DESIGN: The processing interactions characterizing the linguistic and auditory dimensions were assessed with a pediatric auditory analog of the Pomerantz task (Pomerantz, Pristach, & Carson, 1989). The task yields measures of Stroop interference, the effect of irrelevant semantic content, and of Garner interference, the effect of irrelevant linguistic variability (Stroop, 1935; Garner, 1974a). Subjects were 100 normal-hearing children and 60 hearing-impaired children. Subjects were required to attend selectively to the auditory (voice-gender) dimension and to ignore the linguistic dimension. The logic of the task is that performance for the voice-gender dimension will be unaffected by what is happening on the irrelevant dimension if the dimensions are processed independently. On the other hand, if the dimensions are not processed independently, subjects will not be able to attend selectively and performance for the relevant dimension will be affected by what is happening on the to-be-ignored dimension. RESULTS: Both the normal-hearing and hearing-impaired children showed auditory Stroop and Garner interference effects, indicating that the auditory and linguistic dimensions were not processed independently by either group. However, the linguistic dimension exerted significantly less influence on auditory processing in the presence of childhood hearing impairment. Whereas normal-hearing children had remarkable difficulty ignoring irrelevant word input and focusing exclusively on voice-gender, hearing-impaired children were relatively successful at ignoring the linguistic dimension and attending selectively to the auditory dimension of speech. This result implies that the linguistic dimension of auditory speech input may have a different weight or processing value in the presence of childhood hearing impairment. It may be the case that hearing-impaired children encode spoken speech disproportionately in terms of the auditory dimensions, which offer important supplementary aids to speechreading. Further research is being carried out to address these possibilities. CONCLUSIONS: Both Stroop and Garner interference were significantly reduced in the presence of childhood hearing impairment. This pattern of results suggests that multidimensional speech processing is carried out in a less stimulus-bound manner in the presence of childhood hearing impairment.

Auditory stroop effects in children with hearing impairment.

The accurate perception of speech involves the processing of multidimensional information. The aim of this study was to determine the influence of the semantic dimension on the processing of the auditory dimension of speech by children with hearing impairment. The processing interactions characterizing the semantic and auditory dimensions were assessed with a pediatric auditory Stroop task. The subjects, 20 children with hearing impairment and 60 children with normal hearing, were instructed to attend selectively to the voice-gender of speech targets while ignoring the semantic content. The type of target was manipulated to represent conflicting, neutral, and congruent relations between dimensions (e.g., the male voice saying "Mommy," "ice cream," or "Daddy" respectively). The normal-hearing listeners could not ignore the irrelevant semantic content. Instead, reaction times were slower to the conflict targets (Stroop interference) and faster to the congruent targets (Stroop congruency). The subjects with hearing impairment showed prominent Stroop congruency, but minimal Stroop interference. Reduced Stroop interference was not associated with chronological age, a speed-accuracy tradeoff, a non-neutral baseline, or relatively poorer discriminability of the word input. The present results suggest that the voice-gender and semantic dimensions of speech were not processed independently by these children, either those with or those without hearing loss. However, the to-be-ignored semantic dimension exerted a less consistent influence on the processing of the voice-gender dimension in the presence of childhood hearing loss. The overall pattern of results suggests that speech processing by children with hearing impairment is carried out in a less stimulus-bound manner.

Developmental trends in the interaction between auditory and linguistic processing.

The developmental course of multidimensional speech processing was examined in 80 children between 3 and 6 years of age and in 60 adults between 20 and 86 years of age. Processing interactions were assessed with a speeded classification task (Garner, 1974a), which required the subjects to attend selectively to the voice dimension while ignoring the linguistic dimension, and vice versa. The children and adults exhibited both similarities and differences in the patterns of processing dependencies. For all ages, performance for each dimension was slower in the presence of variation in the irrelevant dimension; irrelevant variation in the voice dimension disrupted performance more than irrelevant variation in the linguistic dimension. Trends in the degree of interference, on the other hand, showed significant differences between dimensions as a function of age. Whereas the degree of interference for the voice-dimension-relevant did not show significant age-related change, the degree of interference for the word-dimension-relevant declined significantly with age in a linear as well as a quadratic manner. A major age-related change in the relation between dimensions was that word processing, relative to voice-gender processing, required significantly more time in the children than in the adults. Overall, the developmental course characterizing multidimensional speech processing evidenced more pronounced change when the linguistic dimension, rather than the voice dimension, was relevant.

Screening audiometry using the high-risk register in a level III nursery.

Several factors, including those in the high-risk register, were studied in 1240 graduates of an intensive care nursery who underwent auditory brain-stem response testing. Univariate analysis, with chi 2 and Fisher's Exact Test, and stepwise logistic regression were used to identify variables associated with auditory brain-stem response outcomes. Results suggest that factors in the high-risk register do not carry equal weight and that universal screening in the intensive care nursery may be preferable.

Evaluation of higher-level auditory function in children with asymptomatic congenital cytomegalovirus infection.

Higher-level auditory/cognitive functions were evaluated in 16 children: eight with asymptomatic congenital cytomegalovirus (CMV) infections and eight children documented not to have asymptomatic congenital CMV infections. Hearing sensitivity was within normal limits in all subjects. Results in both groups were within the normal range on the screening measures of verbal abilities, visual perception, social behavior, and memory span. In contrast, results of the auditory measures revealed abnormal dichotic speech perception, delayed latencies on auditory brainstem evoked responses, and disproportionately slow reaction times in a difficult listening condition (Stroop task). With the exception of dichotic speech perception, however, the pattern of auditory results suggested subtle disorders that were difficult to discern unequivocally with the small subject sample. Further studies are encouraged to determine the status of higher-level auditory/cognitive functions in children with asymptomatic congenital CMV infections.

Correlational analysis of speech audiometric scores, hearing loss, age, and cognitive abilities in the elderly.

A battery of speech audiometric measures and a battery of neuropsychological measures were administered to 200 elderly individuals with varying degrees of pure-tone sensitivity loss. Results were analyzed from the standpoint of the extent to which variation in speech audiometric scores could be predicted by knowledge of pure-tone hearing level, age, and cognitive status. For the four monotic test procedures (PB, SPIN-Low, SPIN-High, and SSI) degree of hearing loss bore the strongest relation to speech recognition score. Cognitive status accounted for little of the variance in any of these four speech audiometric scores. In the case of the single dichotic test procedure (DSI), both degree of hearing loss and speed of mental processing, as measured by the Digit Symbol subtest of the WAIS-R, accounted for significant variance. Finally, age accounted for significant unique variance only in the SSI score.

Central auditory processing disorder: a case study.

We carried out extensive audiologic, electrophysiologic, and neuropsychologic testing on a young woman who complained that she had difficulty hearing in her educational environment. Conventional audiometric results, including pure-tone, speech, and immittance audiometry, were all within normal limits. The subject performed normally on tests involving the processing of rapidly changing temporal information, interaural time and intensity difference detection, and both absolute and relative sound localization. Early, middle, late and task-related auditory evoked potentials were essentially normal, although some asymmetry was observed in the middle latency (MLR) and late (LVR) responses. There was, however, a consistent left-ear deficit on dichotic sentence identification, on threshold and suprathreshold speech measures in the left sound field when various types of competition were delivered in the right sound field, and on cued-target identification in the left sound field in the presence of multitalker babble. Results suggest a central auditory processing disorder characterized by an asymmetric problem in the processing of binaural, noncoherent signals in auditory space. When auditory space was structured such that the target was directed to the left ear, and the competition to the right ear, unwanted background was less successfully suppressed than when the physical arrangement was reversed.

Evaluation of adult aphasics with the Pediatric Speech Intelligibility test.

Results of conventional adult speech audiometry may be compromised by the presence of speech/language disorders, such as aphasia. The purpose of this project was to determine the efficacy of the speech intelligibility materials and techniques developed for young children in evaluating central auditory function in aphasic adults. Eight adult aphasics were evaluated with the Pediatric Speech Intelligibility (PSI) test, a picture-pointing approach that was carefully developed to be relatively insensitive to linguistic-cognitive skills and relatively sensitive to auditory-perceptual function. Results on message-to-competition ratio (MCR) functions or performance-intensity (PI) functions were abnormal in all subjects. Most subjects served as their own controls, showing normal performance on one ear coupled with abnormal performance on the other ear. The patterns of abnormalities were consistent with the patterns seen (1) on conventional speech audiometry in brain-lesioned adults without aphasia and (2) on the PSI test in brain-lesioned children without aphasia. An exception to this general observation was an atypical pattern of abnormality on PI-function testing in the subgroup of nonfluent aphasics. The nonfluent subjects showed substantially poorer word-max scores than sentence-max scores, a pattern seen previously in only one other patient group, namely young children with recurrent otitis media. The unusually depressed word-max abnormality was not meaningfully related to clinical diagnostic data regarding the degree of hearing loss and the location and severity of the lesions or to experimental data regarding the integrity of phonologic processing abilities. The observations of ear-specific and condition-specific abnormalities suggest that the linguistically- and cognitively-simplified PSI test may be useful in the evaluation of auditory-specific deficits in the aphasic adult.

Distinguishing auditory and speech-specific perceptual deficits.

The ability to discriminate speech and nonspeech auditory stimuli was tested in a learning disabled child. The perception of speech stimuli was normal when the stimuli were presented in quiet but below normal when the stimuli were presented in noise. Although the perception of pure tone stimuli and environmental sounds was normal both in quiet and noise, the perception of nonspeech stimuli with rapid changes in acoustic information was impaired in noise. These findings illustrate the importance of relating performance for speech and complex nonspeech stimuli in investigating the basis of speech perceptual deficits. Whereas abnormal performance for speech stimuli coupled with normal performance for complex nonspeech stimuli argues for the existence of specialized speech processing mechanisms, abnormal performance for both types of stimuli, as was found in the present subject, argues for the existence of more generalized auditory processing mechanisms.

Dichotic listening in a child with a cerebral lesion: the "paradoxical" ipsilateral ear deficit.

Behavioral testing is reported for a child with a deep, left cerebral lesion that displaced the third ventricle across midline and compressed and elevated the lateral ventricle, presumably disrupting interhemispheric auditory pathways. The onset of the lesion was before 2 1/2 years of age. Cognitive screening tests indicated normal nonverbal (visual perceptual) and semantic (confrontation naming) abilities, but impaired syntactic skills. Audiological testing showed an isolated ipsilateral ear abnormality on dichotic testing only. All other audiological results, including monotic testing with the same speech materials, were normal. Results were comparable to findings in adults with similar lesions.

Speech understanding in the elderly.

Both auditory and cognitive status were determined in 130 elderly persons, in the age range from 51 to 91 years. Data were analyzed from the standpoint of the congruence of auditory and cognitive deficits. The prevalence of central auditory processing disorder was 50%, and the prevalence of cognitive deficit was 41%. Findings in the two areas were congruent, however, in only 63% of the total sample. Central auditory status was abnormal in the presence of normal cognitive function in 23% of subjects. Central auditory status was normal in the presence of cognitive deficit in 14% of subjects. In general, results did not support the hypothesis that decline in speech understanding in the elderly can be explained as the consequence of concomitant cognitive decline.

Pediatric central auditory dysfunction. Comparison of children with confirmed lesions versus suspected processing disorders.

This study compared and contrasted results on pure tone audiometry, acoustic reflexes, and the Pediatric Speech Intelligibility Test in children with either documented or suspected central auditory dysfunction. Ages ranged from 3 years, 2 months, to 8 years, 4 months. In children with confirmed CNS lesions, results were consistently normal for children with lesions in nonauditory areas of the brain and consistently abnormal for children with lesions in areas of the brain important for auditory perceptual function. The patterns of abnormality were consistent with previous findings in adults. In children with suspected central auditory processing disorders (CAPDs), audiometric findings typically showed normal hearing sensitivity, abnormal (rising) audiometric contours, normal acoustic reflexes, normal degraded monotic speech perception, and abnormal dichotic speech perception. This pattern of results was similar to findings in children with confirmed temporal lobe lesions. Overall, results supported an auditory perceptual, rather than a linguistic, basis for CAPDs.

Evidence of echoic memory with a multichannel cochlear prosthesis.

Short-term memory was examined in a subject with a multichannel cochlear prosthesis. Serial recall for lists of digits revealed what are widely regarded as the principal hallmarks of echoic memory, namely the recency effect and the suffix effect. Thus, probability of recall increased for the last one or two digits, except when a nominally irrelevant but spoken item was appended to the to-be-remembered list. It appears, therefore, that a multichannel cochlear implant can give rise to not only the perception of, but also an echoic memory for, speech. As with normal subjects, the suffix effect did not occur with a nonspeech suffix, implying that the echoic memory from the prosthesis shows normal sensitivity to the distinction between speech and nonspeech.

A developmental study of the auditory Stroop effect.

A pediatric auditory version of the Stroop procedure was developed and administered to 48 normal children from 3 to 6 years of age. Our purpose was to define the developmental course characterizing interaction between auditory and semantic speech dimensions in young children. The procedure was a reaction time (RT) task that required children to respond as quickly and as accurately as possible to words spoken by a male or a female voice. Children were instructed to ignore what was said and to push the "Mommy" button if Mommy was talking or the "Daddy" button if Daddy was talking. Performance was obtained for words with neutral, congruent, and conflicting semantic content. Preschool children manifested processing dependencies that were similar to those observed in adults on the visual Stroop procedure. Conflict between semantic and auditory dimensions significantly increased RT and congruence between the two dimensions significantly decreased RT relative to the neutral condition. The pattern of results indicated that the meaning of words was processed automatically in the normal children. The magnitude of the Stroop effect reflected developmental change with increasing age.

Effect of response criterion on measures of speech understanding in the elderly.

Twenty-four elderly subjects were divided into three groups on the basis of response criterion in a signal-detection task. The groups, representing strict, lax, and intermediate listeners, were then compared on the basis of performance on several conventional speech audiometric measures. When the data were corrected for degree of hearing loss, group differences were not significant. Thus, conventional speech audiometric results did not appear to be significantly influenced by response criterion.