Speech Perception in Noise Predicts Oral Narrative Comprehension in Children With Developmental Language Disorder.

We examined the relative contribution of auditory processing abilities (tone perception and speech perception in noise) after controlling for short-term memory capacity and vocabulary, to narrative language comprehension in children with developmental language disorder. Two hundred and sixteen children with developmental language disorder, ages 6 to 9 years (Mean = 7; 6), were administered multiple measures. The dependent variable was children's score on the narrative comprehension scale of the Test of Narrative Language. Predictors were auditory processing abilities, phonological short-term memory capacity, and language (vocabulary) factors, with age, speech perception in quiet, and non-verbal IQ as covariates. Results showed that narrative comprehension was positively correlated with the majority of the predictors. Regression analysis suggested that speech perception in noise contributed uniquely to narrative comprehension in children with developmental language disorder, over and above all other predictors; however, tone perception tasks failed to explain unique variance. The relative importance of speech perception in noise over tone-perception measures for language comprehension reinforces the need for the assessment and management of listening in noise deficits and makes a compelling case for the functional implications of complex listening situations for children with developmental language disorder.

Auditory evoked potentials: Differences by sex, race, and menstrual cycle and correlations with common psychoacoustical tasks.

Auditory brainstem responses (ABRs) and auditory middle-latency responses (AMLRs) to a click stimulus were measured in about 100 subjects. Of interest were the sex differences in those auditory evoked potentials (AEPs), the correlations between the various AEP measures, and the correlations between the AEP measures and measures of otoacoustic emissions (OAEs) and behavioral performance also measured on the same subjects. Also of interest was how the menstrual cycle affected the various AEP measures. Most ABR measures and several AMLR measures exhibited sex differences, and many of the former were substantial. The sex differences tended to be larger for latency than for amplitude of the waves, and they tended to be larger for a weak click stimulus than for a strong click. The largest sex difference was for Wave-V latency (effect size ~1.2). When subjects were dichotomized into Non-Whites and Whites, the race differences in AEPs were small within sex. However, sex and race interacted so that the sex differences often were larger for the White subjects than for the Non-White subjects, particularly for the latency measures. Contrary to the literature, no AEP measures differed markedly across the menstrual cycle. Correlations between various AEP measures, and between AEP and OAE measures, were small and showed no consistent patterns across sex or race categories. Performance on seven common psychoacoustical tasks was only weakly correlated with individual AEP measures (just as was true for the OAEs also measured on these subjects). AMLR Wave Pa unexpectedly did not show the decrease in latency and increase in amplitude typically observed for AEPs when click level was varied from 40 to 70 dB nHL (normal Hearing Level). For the majority of the measures, the variability of the distribution of scores was greater for the males than for the females.

Auditory Brainstem Responses to Successive Sounds: Effects of Gap Duration and Depth.

Temporal acuity is the ability to differentiate between sounds based on fluctuations in the waveform envelope. The proximity of successive sounds and background noise diminishes the ability to track rapid changes between consecutive sounds. We determined whether a physiological correlate of temporal acuity is also affected by these factors. We recorded the auditory brainstem response (ABR) from human listeners using a harmonic complex (S1) followed by a brief tone burst (S2) with the latter serving as the evoking signal. The duration and depth of the silent gap between S1 and S2 were manipulated, and the peak latency and amplitude of wave V were measured. The latency of the responses decreased significantly as the duration or depth of the gap increased. The amplitude of the responses was not affected by the duration or depth of the gap. These findings suggest that changing the physical parameters of the gap affects the auditory system's ability to encode successive sounds.

Community-Based Intervention Determines Tele-Audiology Site Candidacy.

PURPOSE: Sections of the community face barriers to accessing audiology services. The aim of this study was to assess the barriers faced by people in typically underserved community settings and to provide audiology services in their natural environment. Information gathered by questionnaire was used to determine each site's candidacy as a potential tele-audiology site. METHOD: Sixty-three participants were recruited across 3 community sites that were identified as gathering places for individuals who experience barriers to accessing traditional clinical audiology services. Information about demographics and participant experience with barriers to access was gathered by a locally generated, self-administered questionnaire. Pure-tone air-conduction audiometric exams were performed on participants with an automated portable diagnostic audiometer. Afterward, the investigator provided counseling regarding hearing loss rehabilitation or hearing protection. Referrals were made when appropriate. RESULTS: Pure-tone averages were similar within sites but varied across sites. At least 30% of individuals at each site reported they wanted to visit the audiologist more often. Each site reported different principal barriers to access, among them transportation, motivation, and money. Eleven individuals were referred to the next level of care. Questionnaire results revealed special accommodations should be considered at each potential tele-audiology site. CONCLUSION: The present study provided audiology services to individuals in their natural environment, identified many of the obstacles preventing individuals from pursuing traditional audiology services and provided information for the foundation of a tele-audiology practice.

Otoacoustic emissions, auditory evoked potentials and self-reported gender in people affected by disorders of sex development (DSD).

Both otoacoustic emissions (OAEs) and auditory evoked potentials (AEPs) are sexually dimorphic, and both are believed to be influenced by prenatal androgen exposure. OAEs and AEPs were collected from people affected by 1 of 3 categories of disorders of sex development (DSD) - (1) women with complete androgen insensitivity syndrome (CAIS); (2) women with congenital adrenal hyperplasia (CAH); and (3) individuals with 46,XY DSD including prenatal androgen exposure who developed a male gender despite initial rearing as females (men with DSD). Gender identity (GI) and role (GR) were measured both retrospectively and at the time of study participation, using standardized questionnaires. The main objective of this study was to determine if patterns of OAEs and AEPs correlate with gender in people affected by DSD and in controls. A second objective was to assess if OAE and AEP patterns differed according to degrees of prenatal androgen exposure across groups. Control males, men with DSD, and women with CAH produced fewer spontaneous OAEs (SOAEs) - the male-typical pattern - than control females and women with CAIS. Additionally, the number of SOAEs produced correlated with gender development across all groups tested. Although some sex differences in AEPs were observed between control males and females, AEP measures did not correlate with gender development, nor did they vary according to degrees of prenatal androgen exposure, among people with DSD. Thus, OAEs, but not AEPs, may prove useful as bioassays for assessing early brain exposure to androgens and predicting gender development in people with DSD.

Relationships between otoacoustic emissions and a proxy measure of cochlear length derived from the auditory brainstem response.

Brief tones of 1.0 and 8.0 kHz were used to evoke auditory brainstem responses (ABRs), and the differences between the wave-V latencies for those two frequencies were used as a proxy for cochlear length. The tone bursts (8 ms in duration including 2-ms rise/fall times, and 82 dB in level) were, or were not, accompanied by a continuous, moderately intense noise band, highpass filtered immediately above the tone. The proxy values for length were compared with various measures of otoacoustic emissions (OAEs) obtained from the same ears. All the correlations were low, suggesting that cochlear length, as measured by this proxy at least, is not strongly related to the various group and individual differences that exist in OAEs. Female latencies did not differ across the menstrual cycle, and the proxy length measure exhibited no sex difference (either for menses females vs. males or midluteal females vs. males) when the highpass noises were used. However, when the subjects were partitioned into Whites and Non-Whites, a substantial sex difference in cochlear length did emerge for the White group, although the correlations with OAEs remained low. Head size was not highly correlated with any of the ABR measures.

Assessing the double phonemic representation in bilingual speakers of Spanish and English: an electrophysiological study.

Event Related Potentials (ERPs) were recorded from Spanish-English bilinguals (N=10) to test pre-attentive speech discrimination in two language contexts. ERPs were recorded while participants silently read magazines in English or Spanish. Two speech contrast conditions were recorded in each language context. In the phonemic in English condition, the speech sounds represented two different phonemic categories in English, but represented the same phonemic category in Spanish. In the phonemic in Spanish condition, the speech sounds represented two different phonemic categories in Spanish, but represented the same phonemic categories in English. Results showed pre-attentive discrimination when the acoustics/phonetics of the speech sounds match the language context (e.g., phonemic in English condition during the English language context). The results suggest that language contexts can affect pre-attentive auditory change detection. Specifically, bilinguals' mental processing of stop consonants relies on contextual linguistic information.

Differences by sex, ear, and sexual orientation in the time intervals between successive peaks in auditory evoked potentials.

Auditory evoked potential (AEP) data from two studies originally designed for other purposes were reanalyzed. The auditory brainstem response (ABR), middle-latency response (MLR), and long-latency response (LLR) were measured. The latencies to each of several peaks were measured for each subject for each ear of click presentation, and the time intervals between successive peaks were calculated. Of interest were differences in interpeak intervals between the sexes, between people of differing sexual orientations, and between the two ears of stimulation. Most of the differences obtained were small. The largest sex differences were for interval I → V in the ABR and interval N1 → N2 of the LLR (effect sizes > 0.6). The largest differences between heterosexuals and nonheterosexuals were for the latency to Wave I in both sexes, for the interval Na → Nb in females, and for intervals V → Na and Nb → N1 in males (effect sizes > 0.3). The largest difference for ear stimulated was for interval N1 → N2 in heterosexual females (effect size ∼0.5). No substantial differences were found in the AEP intervals between women using, and not using, oral contraceptives. Left/right correlations for the interpeak intervals were mostly between about 0.4 and 0.6. Correlations between the ipsilateral intervals were small; i.e., interval length early in the AEP series was not highly predictive of interval length later in the series. Interpeak intervals appear generally less informative than raw latencies about differences by sex and by sexual orientation.

Testing the double phonemic boundary in bilinguals.

It is widely known that language influences the way speech sounds are categorized. However, categorization of speech sounds by bilinguals is not well understood. There is evidence that bilinguals have different category boundaries than monolinguals, and there is evidence suggesting that bilinguals' phonemic boundaries can shift with language context. This phenomenon has been referred as the double phonemic boundary. In this investigation, the double phonemic boundary is tested in Spanish-English bilinguals (N = 18) and English monolinguals (N = 16). Participants were asked to categorize speech stimuli from a continuum ranging from /ga/ to /ka/ in two language contexts. The results showed phonemic boundary shifts in bilinguals and monolinguals which did not differ across language contexts. However, the magnitude of the phoneme boundary shift was significantly correlated with the level of confidence in using English and Spanish (reading, writing, speaking, and comprehension) for bilinguals, but not for monolinguals. The challenges of testing the double phonemic boundary are discussed, along with the limitations of the methodology used in this study.

The efficacy of Fast ForWord Language intervention in school-age children with language impairment: a randomized controlled trial.

PURPOSE: A randomized controlled trial was conducted to compare the language and auditory processing outcomes of children assigned to receive the Fast ForWord Language intervention (FFW-L) with the outcomes of children assigned to nonspecific or specific language intervention comparison treatments that did not contain modified speech. METHOD: Two hundred sixteen children between the ages of 6 and 9 years with language impairments were randomly assigned to 1 of 4 conditions: (a) Fast ForWord Language (FFW-L), (b) academic enrichment (AE), (c) computer-assisted language intervention (CALI), or (d) individualized language intervention (ILI) provided by a speech-language pathologist. All children received 1 hr and 40 min of treatment, 5 days per week, for 6 weeks. Language and auditory processing measures were administered to the children by blinded examiners before treatment, immediately after treatment, 3 months after treatment, and 6 months after treatment. RESULTS: The children in all 4 conditions improved significantly on a global language test and a test of backward masking. Children with poor backward masking scores who were randomized to the FFW-L condition did not present greater improvement on the language measures than children with poor backward masking scores who were randomized to the other 3 conditions. Effect sizes, analyses of standard error of measurement, and normalization percentages supported the clinical significance of the improvements on the Comprehensive Assessment of Spoken Language (E. Carrow-Woolfolk, 1999). There was a treatment effect for the Blending Words subtest of the Comprehensive Test of Phonological Processing (R. K. Wagner, J. K. Torgesen, & C. A. Rashotte, 1999). Participants in the FFW-L and CALI conditions earned higher phonological awareness scores than children in the ILI and AE conditions at the 6-month follow-up testing. CONCLUSION: Fast ForWord Language, the intervention that provided modified speech to address a hypothesized underlying auditory processing deficit, was not more effective at improving general language skills or temporal processing skills than a nonspecific comparison treatment (AE) or specific language intervention comparison treatments (CALI and ILI) that did not contain modified speech stimuli. These findings call into question the temporal processing hypothesis of language impairment and the hypothesized benefits of using acoustically modified speech to improve language skills. The finding that children in the 3 treatment conditions and the active comparison condition made clinically relevant gains on measures of language and temporal auditory processing informs our understanding of the variety of intervention activities that can facilitate development.

Sensory processing of backward-masking signals in children with language-learning impairment as assessed with the auditory brainstem response.

The purpose of this study was to examine the possible contribution of sensory mechanisms to an auditory processing deficit shown by some children with language-learning impairment (LLI). Auditory brainstem responses (ABRs) were measured from 2 groups of school-aged (8-10 years) children. One group consisted of 10 children with LLI, and the other group (control) consisted of 10 children with normally developing language. The ABR was elicited with a brief tone burst presented either alone (no-masking condition) or immediately followed by a longer duration noise burst (backward-masking condition). The primary dependent variable was the latency of wave V of the ABR. The mean latencies were not significantly different for the 2 groups in the no-masking condition. However, in the backward-masking condition, the mean latency for the LLI group was significantly increased relative to the mean latency for the control group. Thus, the presence of successive sounds delay the neural response in children with LLI. The explanation for this delay at the level of the brainstem is not known, but it may be due to disruption of synchrony, activation of alternate (less direct) pathways, increased inhibition, or some combination of these (or other) factors.

Evaluation of distortion products produced by the human auditory system.

During the simultaneous monaural presentation of two primary tones, distortion products can be measured acoustically in the ear canal (DPOAEs) and electrically as auditory evoked potentials (DPAEPs). The purpose of this investigation was to elucidate the sources of nonlinearity within the human auditory system responsible for generating quadratic (QDT) and cubic (CDT) difference tones. Measurements of DPOAEs and DPAEPs were obtained from 24 normal-hearing adults (12 male) in conditions with and without presentation of a 60 dB SPL contralateral noise. The effects of primary-tone signal duration and mode of presentation on measurements of DPAEPs were also examined. Results indicated that overall, both acoustic and electric distortion products were suppressed during presentation of a contralateral noise. Increases in the duration of the primary tones caused increases in DPAEP amplitudes. A greater proportion of individuals exhibited DPAEPs with monotic compared to dichotic presentation of the primary tones. The findings of the investigation supported the conjecture that a cochlear nonlinearity produced CDT acoustic and electric distortion products. Evidence concerning the origin of the QDT DPAEP was inconclusive, and contributions from both cochlear and neural nonlinear sources could not be ruled out.

Reception thresholds for sentences in bilingual (Spanish/English) and monolingual (English) listeners.

Recent evidence on the perceptual performance of bilingual listeners suggests that a nonaudibility-based cost exists in processing a second language. That is, when compared to monolingual English speakers and early bilinguals, listeners who acquired English as a second language after puberty show reduced performance when listening to the second language in background noise, despite normal auditory thresholds. However, past studies have not controlled for the homogeneity of the bilingual participants used in auditory research; therefore, it is unknown whether the deficit observed in bilingual function is due to a lack of control for language-related variables. The ability of a homogeneous group of Spanish-English bilinguals and English monolingual listeners to perceive sentences in quiet and in noise at threshold levels was evaluated using the Hearing in Noise Test (HINT). Both groups performed similarly in quiet conditions. In the noise conditions, the bilingual group's performance was significantly poorer than the monolingual group's performance. However, both groups showed a binaural advantage of 7-8 dB when the signal and noise were separated by 90 degrees.

Auditory memory for backward masking signals in children with language impairment.

This study was designed to investigate early auditory memory and its possible contribution to an auditory processing deficit shown by some children with language impairment. Ten children with language impairment and 10 age-matched controls participated in a series of simultaneous and backward masking tasks. The same backward masking stimulus was then used to elicit a mismatch negativity response. In the behavioral conditions, children in the language impairment group had significantly higher (poorer) signal thresholds than their nonimpaired controls in backward masking, but their thresholds in simultaneous masking were not significantly different. In the mismatch-negativity conditions, latency was prolonged and the amplitude was diminished in the children with language impairment. Taken together, these psychoacoustic and electrophysiological data suggest that in a group of children with language impairment, underlying the nonsensory language disorder, there is a neurophysiological impairment in auditory memory for complex, nonlinguistic sounds.