Audiology : official organ of the International Society of Audiology最新文献

Transient-evoked otoacoustic emissions (TEOAEs) were obtained from 688 ears of a group of 345 young adults aged 18 to 25 years, using the Otodynamics ILO88 in the standard, non-linear mode. Normative data for TEOAEs obtained from 186 otologically normal (ON) ears are presented. In 5 ON ears, there was no recordable response, despite hearing threshold levels better than 20 dB. The main factors affecting the TEOAE level were (1) gender, where females had larger responses on average than males; (2) tympanometric measures, where ears with entirely normal tympanometric measures had larger responses than those with minor tympanometric abnormalities; (3) click stimulus intensity measured in the ear canal, which correlated positively with TEOAE level; and (4) hearing threshold level at 0.5 kHz, which correlated negatively with amplitude. There was also a small effect of social noise exposure in the 2-kHz region of the TEOAE, where the response was lower in those subjects exposed to significant social noise.

We have found a reorganization of tonotopic maps (based on neuron response thresholds) in primary auditory cortex of the adult chinchilla after amikacin-induced basal cochlear lesions. We find an over-representation of a frequency that corresponds to the border area of the cochlear lesion. The reorganization observed is similar in extent to that previously seen in a developmental model. The properties of neurons within the over-represented area were investigated in order to determine whether their responses originated from a common input (an indication of true plasticity) or represented only the result of truncating the activity of the sensory epithelium ("pseudo-plasticity"). Some aspects of our data fit with a true plasticity model and indicate the potential for the deafferented cortex of the mature cortex to regain connections with the surviving sensory epithelium.

This paper examines a possible procedure for a clinical gap-detection test that is simple, frequency specific, and reliable. A cued yes-no method of maximum likelihood (MML) procedure was compared to an up-down three-interval, two-alternative, forced-choice procedure. Results from five trained and seven naive listeners indicate that the yes-no MML procedure yields valid and efficient estimates of narrowband gap-detection thresholds. Preliminary tests yield encouraging results.

The objective of this case-report study was to assess the presence of central auditory impairment in a patient with a normal neurological examination. This subject was a 45-year-old female with gradually deteriorating hearing difficulties over a period of 5 years and a borderline normal audiogram. Behavioural central auditory tests were used, including Dichotic Sentence Identification Test, Competing Sentences Test, and auditory event-related potentials (mismatch negativity). Behavioural central auditory tests and mismatch negativity results were abnormal and indicated disordered central auditory processing. Subsequent magnetic resonance imaging of the brain identified subtle changes consistent with small-vessel ischaemic disease. Adult patients who present with hearing difficulties that cannot be explained on the basis of their audiogram should undergo central auditory assessment, as the auditory symptoms may be the first and only manifestation of central nervous system pathology.

Linear and QuickScreen (non-linear) transient evoked otoacoustic emission (TEOAE) protocols were compared in terms of standardized clinical parameters in order to define the protocol producing recordings with the highest signal quality. Neonatal responses (520) were obtained from three different screening sites. The linear recordings were evoked by 69 and 75-dB p.e. SPL clicks. All responses were post-windowed by a 3.5- to 12.5-ms window, chosen by time-frequency analysis as the segment representing 97.35 per cent (linear) and 95.6 per cent (quick) of the total cumulative spectral energy. Evidence from hearing loss cases and the high similarity between the profile contours of the QuickScreen and the linear normal recordings have strongly suggested that a linear response evoked by a 75-dB p.e. SPL stimulus and post-processed by a 3.5 to 12.5 window is free of stimulus artefacts. The data indicate that the 75-dB linear protocol produces higher signal to noise ratios at 2.0, 3.0, and 4.0 kHz, higher wave reproducibility, and lower TEOAE noise values than the QuickScreen protocol.

The focus in this study is on social competence and behavioural problems in a group (n=57) of hearing-impaired 7- to 12-year-old children. Results were related to hearing status, school placement, and gender. Parent and teacher questionnaires were used to measure two aspects of social competence, prosocial orientation and social initiative, and three aspects of behavioural problems, externalizing, internalizing, and concentration problems. A sample of 214 normally-hearing children was used as a comparison group. Overall, the results showed only minor differences between the two groups, with the exception that the hearing-impaired children showed less social initiative in parent ratings. There were no relationships between social functioning and hearing status or school placement (mainstream vs. special classes for hearing-impaired children) nor any clear pattern of gender differences. These findings indicate that hearing-impaired children in Sweden fare well. The results are discussed in terms of the need for longitudinal studies and possible interventions targeted at social behaviours.

Over-the-counter hearing aids (OTCs) are those directly purchased from retail outlets, without the benefit of prior professional hearing health care. They are particularly common in developing countries. This study examined the amplification characteristics of a selected sample of OTCs to determine if any target client group or groups were suitable for the OTCs. The electroacoustical performance of 10 OTCs was measured. The measurements included saturated sound pressure level curve, high-frequency average full-on gain, frequency response, total harmonic distortion, equivalent input noise level, and input-output curve. The full-on gain curve of each hearing aid was used to estimate the hypothetical hearing loss of target clients for each aid as it would be calculated by four hearing aid prescription formulae. Real-ear probe tube measurements were also performed on 10 adult subjects to determine the amplification that could be achieved by the OTCs before audible feedback occurred. The OTC hearing aids were not able to meet the prescription gain requirements of the majority of elderly clients who usually purchased them.

The ability of native Mandarin-speaking, hearing-impaired subjects to detect Mandarin tones was assessed in this study. Nine subjects with mild sensorineural hearing loss (SNHL) and nine subjects with moderate SNHL participated in the study. Nine normal subjects served as control. All subjects received a tone detection test and Chinese word recognition test. The results show that tone detection was only minimally impaired in the mild SNHL group if audibility of the stimulus is well compensated for. In the moderate SNHL group, the mean score was significantly lower, but the difference was small. This suggests that tone detection is only slightly impaired for subjects with moderate hearing loss. For each individual tone, the mean scores for tones 2 and 3 were lowest and most easily confused by all normal and hearing-impaired subjects. No significant correlation was found between the tone detection score and word recognition score for all subjects. The relatively preserved ability to perceive tones in mild and moderate SNHL subjects may be helpful in their speech recognition.

Dichotic listening was evaluated in free-recall and directed-recall (pre-cued, post-cued) response conditions using interleaved one-, two-, and three-pair dichotic digit materials. In the free-recall condition, the subjects recalled in any order the digits presented. In the directed-recall condition, a response task was examined where subjects recalled all digits presented to the cued ear (pre- or post-cued) followed by the digits presented to the opposite (non-cued) ear. Thirty 20- to 29-year-old adults with normal hearing and 30 60- to 79-year-old adults with mild-to-moderate sensorineural hearing loss were evaluated. In all conditions, performance by the younger listeners was better than performance by the elderly listeners. As the difficulty of the dichotic digit task increased, recognition performance decreased. The recognition performance of elderly listeners was more affected by increases in the difficulty of the stimulus materials as compared to the younger listeners. In the free-recall condition, there was a right-ear advantage for both age groups. When instructional bias was imposed, the results favored the ear of instructed bias. The differences in recognition performance between young and elderly listeners likely reflect differences in the difficulty of the dichotic digit test conditions and variations in the demand on auditory memory.

The present study evaluates the short-term effect of cochlear implantation on the fundamental frequency (FO) of 13 deaf patients. All patients were provided with the Combi 40+ cochlear implant. Voice recording was made pre- and 3 months post-implantation. The FO was analysed using X-Tools software. The results showed that 38 per cent of our subjects had a statistically significant decrease of their mean F0 (p=0.001) at 3 months following implantation. It was also observed that the patients tended to have a lower F0 postoperatively approaching the normal range of F0. A large variability in F0 was noticed among the deaf subjects but no correlation with the duration of deafness was seen. There was also no correlation between speech recognition and speech production.