摘要:

Magnetic resonance imaging (MRI) was used to obtain measures presumed to scale the dimensions of the lower auditory pathway in humans for the purpose of further defining the relationship between length of the auditory pathway and auditory brain stem response (ABR) latencies. Specifically, measurements of soft tissue structures, that is, the eighth nerve and brain stem, were made for comparison with skull dimensions and ABR latencies. It was hypothesized that the brain stem dimensions covary significantly with skull dimensions and that the ABR parameters covary with both skull and brain stem dimensions. In general, only weak correlations were obtained with coefficients failing to reach statistical significance for most comparisons. These findings suggest that variance in ABR latencies cannot be attributed completely to variance in brain stem dimensions and raise suspicion that skull dimensions do not directly reflect brain stem dimensions.

ISSN:0196-0202    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

Several investigators have suggested that the use of tonal stimuli shaped with nonlinear windowing functions can improve the frequency specificity of the auditory brain stem response (ABR). This study investigated the effects of different windowing functions on the ABR for 30 normal-hearing adults and 30 adults with high-frequency hearing loss. These hearing-impaired patients often produce an abnormal click-evoked ABR because of the influence of the high-frequency loss. Each subject was evaluated using a click stimulus and a 500 Hz tone burst gated with one linear and four nonlinear windowing functions. There were no significant differences in wave V latency between the groups for any of the five windowed tone burst conditions. These results suggest that any of the windowing functions used would be effective for 500 Hz tonal ABRs with this population of hearing-impaired adults.

ISSN:0196-0202    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

The onset and frequency-following response (FFR) components of the auditory brain stem response were investigated using a tone on tone forward-masking paradigm, as an alternate strategy to simultaneous masking, in an effort to further clarify the issue of place specificity of these components when elicited by a low-frequency stimulus (500 Hz tone burst). The results of this preliminary investigation suggest that both the onset and FFR components yield frequency-specific information, that is, they reflect activity along a limited apicalward region of the cochlea, but both are biased somewhat basalward to the place of the probe frequency. Also, of the two, the FFR is the relatively more place-specific response.

ISSN:0196-0202    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

The effect of audiometric configuration on the auditory brain stem response was studied in a large patient sample, and wave I latencies, wave V latencies, and the I-V interwave intervals were compared to those from a previous report. Patients with notched hearing losses showed longer wave V latencies and I-V interwave intervals than those with other audiometric configurations, but the magnitude of the effect was relatively small, and the confidence limit for cochlear diagnosis was essentially the same as that based upon a cochlear hearing loss population without regard to audiometric configuration.

ISSN:0196-0202    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

This study investigated strategies for increasing the number of responses that can be obtained from young children during visual reinforcement audiometry. Subjects included normal 1- and 2-yr-old children. Responses before habituation were studied as a function of age, reinforcer conditions, and test sessions. It was found that: (1) using two reinforcers led to more responses before habituation than use of a single reinforcer; (2) after habituation in test session 1 and a 10-min break, most 1-yr-olds demonstrated a minimum of five additional responses in test session 2; and (3) 2-yr-olds habituated more rapidly than 1-yr-olds.

ISSN:0196-0202    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

Obscure Auditory Dysfunction (OAD) is defined as a clinical referral for self-reported auditory disability with no audiometric abnormality by stringent criteria. In stage 2 of a case control study of OAD, we have confirmed the general finding of stage 1 that OAD is multifactorial; compared with controls, patients as a group have a genuine performance deficit for understanding speech in noise, accompanied by personality-related factors. Paired logistic regression analysis optimally differentiated the 50 patients from their 50 matched controls on the basis of variables from three different domains: masked thresholds (psychoacoustic domain), dichotic listening ability (central/cognitive domain), and underestimation of own hearing ability (personality domain). A further and influential contributing variaMe was understanding of speech in noise supplementing the variables in both the psychoacoustic and the cognitive domains. With this model, 82.7% of the total group deviance was explained (i.e., the binary variable of case/control). A corresponding discriminant function analysis correctly classified 80% of patients and 90% of controls. When factors underlying the performance and personality-related variables were investigated with multiple linear regression within the two groups separately, relatively little of the within-group variance among OADs was explained. This is consistent with the multifactorial nature of OAD, in that the combinations of factors leading to OAD status differ between individuals. The research findings have been used to design a clinical test package to provide diagnostic information on the basis of OAD in individuals.

ISSN:0196-0202    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

This study assessed the efficacy of an adaptive frequency response hearing aid (AFR) for improving speech perception ability in noise among a group of elderly hearing-impaired listeners. A speech recognition task, self-assessed speech intelligibility task, and qualitative judgment task were administered to examine subtle differences in the effects of the AFR “signal processing” versus linear amplification. Group scores showed statistically significant improvement with AFR processing on the speech recognition task involving high-predictability sentences, but not on any other measures. However, there was a trend toward improved scores with AFR processing for low-predictability sentences as well. These results suggest that AFR circuitry may be most useful for enhancing recognition of speech in high-cue contexts. Wide individual subject variability was observed on all measures. This demonstrates the importance of evaluating the effectiveness of noise reduction hearing aids on an individual basis and with more than one task.

ISSN:0196-0202    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

The recognition of phonemes in consonant-vowel-consonant words, presented in speech-shaped random noise, was measured as a function of signal to noise ratio (S/N) in 10 normally hearing adults and 10 successful adult users of the Nucleus cochlear implant. Optimal scores (measured at a S/N of +25 dB) were 98% for the average normal subject and 42% for the average implantee. Phoneme recognition threshold was defined as the S/N at which the phoneme recognition score fell to 50% of its optimal value. This threshold was −2 dB for the average normal subject and +9 dB for the average implantee. Application of a digital noise suppression algorithm (INTEL) to the mixed speech plus noise signal had no effect on the optimal phoneme recognition score of either group or on the phoneme recognition threshold of the normal group. It did, however, improve the phoneme recognition threshold of the implant group by an average of 4 to 5 dB. These findings illustrate the noise susceptibility of Nucleus cochlear implant users and suggest that single-channel digital noise reduction techniques may offer some relief from this problem.

ISSN:0196-0202    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

We report results on a cued-listening task designed to simulate the listening problems commonly described by individuals with sensorineural hearing loss, especially those experienced by elderly persons. Against a background of multitalker babble, the subject detected targets embedded in continuous discourse. Noncoherent segments of this discourse were presented simultaneously from loudspeakers on the right and left sides. A signal light cued the side to be monitored during a listening trial. The overall difficulty of the task was manipulated by variation of the message to competition intensity ratio. A sequence of listening trials, half-cued to the right side, half cued to the left side, was executed at each of four message to competition intensity ratios. Nineteen young adults with normal hearing and 28 elderly persons with presbyacusic hearing loss were evaluated. All subjects, young and elderly, were able to complete the cued-listening task successfully. Results showed a small but significant right-side advantage in the young group and a substantial right-side advantage in the elderly group. The application of the testing technique to the evaluation of hearing aid performance is illustrated in two elderly persons.

ISSN:0196-0202    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

We previously examined central auditory processing disorders and the effect of age in 1026 64- to 93-yr-olds. Here, we correlated three indices of central auditory processing disorders with age, pure tone averages (PTA) and maximum word recognition scores. With one exception, correlations of indices with PTA equaled or exceeded those with age. With one exception, correlations with word recognition scores were insignificant or smaller than those with age. Although statistically significant, the magnitudes of most effects were small (0.003 < r2< 0.146). However, PTA accounted for approximately 30% of the variability in corrected Staggered Spondaic Word test error scores.

ISSN:0196-0202    

出版商:OVID    

年代:1992

数据来源: OVID