Scandinavian audiology. Supplementum最新文献

Three groups of young people, in all 10 males and 11 females, with different music listening habits listened to their own choice of music from a portable cassette player for one hour. The sound pressure level from the music was measured with a probe-provided miniature microphone in the external auditory canal close to the tympanic membrane. The temporary threshold shift induced by the music, as well as by 1/3-octave band noise, was registered with Békéky audiometry. The females had significantly more temporary threshold shift than the males after noise-exposure. Most subjects had only discrete temporary threshold shifts after one hour of listening to music, in spite of 91-97 dB listening levels. There were no significant differences in listening levels or music-induced threshold shifts between genders, although such differences were found between groups with different listening habits.

As it has been demonstrated in many animal experiments, noise can damage the cochlea and the central auditory pathways. It is very difficult in clinical studies to separate the relative contribution of both these sites. Auditory evoked potentials ABR, MLR and SVR study retrocochlear nervous conduction and collectively the results of these techniques proved an objective evaluation of the cochlear function. The Authors have studied a group of 130 sport shooters with high frequency hearing loss and found that in 38 ears a clear retrocochlear component could be recognised. Correlation with intensity, frequency and length of exposure to the traumatic noise demonstrates that explosive noise is an agent for NIHL. However athletes exposed to similar noises did not suffer from similar hearing loss, probably because of the well known individual noise susceptibility.

Speech tests comprise an important and integral part of any assessment of the effectiveness of intervention for hearing disability and handicap. Particularly when considering hearing aid services for adult listeners, careful consideration has to be given to the particular form and application of inferences drawn from speech identification procedures if erroneous conclusions are to be avoided. It is argued that four such components relate to the statistical properties and discriminatory leverage of speech identification procedures, the choice of presentation level and conditions in regard to the auditory environment experienced by hearing-impaired clients, the extent to which speech tests based on segmental intelligibility provide appropriate information in relationship to perceived disabilities and handicaps, and the ways in which speech identification procedures to evaluate the potential benefits of signal-processing schemes for hearing aids are dependent upon sufficient listening experiences. Data are drawn from the literature to illuminate these points in terms of application in clinical practice and clinical evaluation exercises, and also with regard to future research needs.

Cognitive psychologists have known for a long time that language and memory are intimately related in people who can hear. Why should the situation be any different for deaf children and deaf adults? This article considers the results of previous studies and some new findings in examining the possible impact of spoken language and sign language fluencies/preferences on the structure and process of memory in deaf individuals. Current evidence suggests that there are some differences in the organization of long-term memory in deaf as compared to hearing people, but no one has yet demonstrated such differences to be so large that they qualitatively or quantitatively affect learning in any real sense. In contrast, there is now abundant evidence to suggest that variation in spoken language abilities have a direct impact on memory span and perhaps on working memory more generally. These findings are discussed in terms of their implications for the education of students who are deaf or hard of hearing.

Aging is associated with a down-regulation in metabolism, which may underlie an increased sensitivity to stress agents and a decreased repair of tissues following stress. In the auditory system this could lead to increased sensitivity to noise induced hearing loss (NIHL) with age. This study examines the effects of high intensity noise exposure (0.5-40 kHz noise at 108 dB SPL for 45 min) on young and old normal (CBA/Ca) mice and young premature presbycusis (C57BL/6) mice. Tone evoked auditory brainstem response (ABR) audiograms were obtained before and after the exposure. The animals were sacrificed and cytocochleograms were performed. The ABR threshold shifts and hair cell losses which followed noise exposure increased with increasing age in the normal (CBA/Ca) mice. Subjects which showed early presbycusis (C57BL/6) associated with vascular pathology, showed an increased sensitivity to noise induced hearing loss over normal subjects. Interestingly, in some cases the physiological loss in C57BL/6 mice was not associated with hair cell loss. These findings support the view that aging with or without hearing loss increased the sensitivity of the ear to NIHL. However, it seems that other factors may contribute to NIHL in the animals with premature presbycusis.

To better understand the nature of mechanical changes following exposure to high-level impact noise, normal cochleas and cochleas from chinchillas exposed to either 125 or 131 dB SPL noise were stained with phalloidin for F-actin and examined using confocal microscopy. As seen in previous experiments, 125 dB exposures produced much more variable results than 131 dB exposures. Some cochleas were relatively unscathed by the exposure, whereas others showed damage to outer hair cells (OHCs) immediately after the exposure that included gross distortions of cell bodies and reduced F-actin in cuticular plates. Twenty-four hours later, there was also disorientation of actin filaments in supporting cells. After 30 days, Deiters cells were disarrayed and cups were separated from OHC neural poles. Exposure to noise at a level of 131 dB SPL produced less variable results than 125 dB exposure, and damage was generally more widespread and severe.

Chickens were exposed to an intense pure tone that destroyed the hair cells and tectorial membrane in a crescent shaped patch along the abneural edge of the basilar papilla. During the following weeks, when the hair cells and tectorial membrane were regenerating, psychophysical and electrophysiological measures were obtained to assess the time course and degree of recovery. Immediately after the exposure, the behavioral thresholds were elevated 30-40 dB and auditory temporal integration was greatly reduced; however, both measures fully recovered by 28 days post-exposure. In addition, tone-on-tone masking patterns recovered to normal. Immediately after the exposure, the thresholds of single cochlear ganglion neurons were elevated more than 30 dB, tuning curves were broader than normal, two-tone rate suppression (TTRS) boundary slopes were shallower than normal and spontaneous activity was reduced. Threshold and spontaneous discharge rate fully recovered after the exposure. Tuning and TTRS also recovered significantly in most neurons; however, some units with characteristic frequencies (CFs) near the exposure frequency showed abnormal tuning and TTRS suppression. The regeneration of the hair cells and lower honeycomb layer of the tectorial membrane is associated with considerable recovery of function; however, the incomplete recovery of tuning and TTRS in some neurons may be linked to the incomplete regeneration of the tectorial membrane.

Communication involves sending and receiving signals. However, it is also a form of social engagement. Constraints on communication between deaf and hearing persons often result in strained interactions as well as los of "full" information. In this paper, a meta-ethnographic approach is used to describe the impact of "spoiled" communication on social engagement between deaf and hearing persons.

Three different non-linear digital signal processing algorithms were developed; LinEar, DynEar and RangeEar. All three provided individual frequency shaping via a seven-band low-power filterbank and compression in two channels. RangeEar and DynEar used wide dynamic range syllabic compression in the low-frequency (LF) channel, while LinEar used compression limiting. In the high-frequency (HF) channel, RangeEar used a slow-acting automatic volume control, while DynEar and LinEar used compression limiting. Wearable digital signal processing-based experimental instruments were used to evaluate the fitting algorithms under real world conditions with experienced hearing aid users. Evaluation included laboratory testing of speech recognition in noise and questionnaires on sound quality ratings. Results did not indicate one general good-for-all algorithm, but different algorithms resulting in preference and performance depending on the hearing loss configuration. Preference for any of the new algorithms could be predicted based on auditory dynamic range measurements. It was hypothesized that the different preferences were affected by different susceptibility to masking of HF sounds by amplified LF sounds.

Some cortical correlates of (silent) speechreading in normal people are described and contextualized with respect both to seeing faces and to hearing speech. Some preliminary work with two people with abnormal language is described, as are some findings concerning evoked responses to seen speech. Superior temporal cortical areas (classical 'speech association' areas) are strongly and specifically implicated in seeing silent speech. In addition, primary auditory cortex can be activated by silent speechreading in hearing people. The implications of these findings for deafness and for issues of compensation and plasticity are outlined.