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At least 181 records · Page 10Linked to original sources

Trimethyltin disrupts loudness recruitment and auditory threshold sensitivity in guinea pigs.

Trimethyltin (TMT) impairs auditory thresholds within minutes of systemic administration. However, there are no data which relate to the output of the auditory nerve at sound levels above threshold. In this experiment, we evaluated the functional effects of TMT on the auditory threshold by identifying the sound level which just produced a detectable compound action potential (CAP). We also assessed outer hair cell function by measuring the cochlear microphonic (CM), a nonpropagated ac potential which is phase-locked to the stimulus. Finally, we measured the growth of the N1 amplitude as a function of stimulus intensity at levels above threshold and of the summating potential (SP), a dc potential which has multiple generators. To isolate cochlear from systemic effects of TMT, the agent was applied directly to the round window, a structure separating the middle and inner ear, of anaesthetized guinea pigs. We show that TMT applied to the round window membrane can disrupt the function of the cochlea. Measurements of auditory function at supra-threshold levels showed clearly that TMT reduced the amplitude of N1 while having no measurable effect on the SP. These findings indicate that TMT blocks the recruitment of neuronal elements by loud sound. This pattern of impairment differs from that observed with aminoglycoside antibiotics, hypothermia, and presbycusis in which loudness recruitment has been reported.

Action Potentials↗

Auditory brainstem response in pediatric migraine: during the attack and asymptomatic period.

OBJECTIVE: The aim of this study was to evaluate the hearing parameters of children with migraine during ictal and interictal period. METHOD: 16 pediatric patients with migraine and normal otolaryngologic examination were evaluated. Hearing parameters were assessed with auditory brainstem response (ABR) testing between and during the migraine attacks. Binaural absolute latencies of waves I, III and V, interpeak latencies I-III, III-V and I-V of ABR in response to 80 dB nHL clicks were calculated. Initial findings were compared with those of 20 healthy volunteers. RESULTS: Peak latencies of wave V and interpeak latencies of I-V were prolonged during the attack in migraineurs on the left. The side of latency elongation was not affected by the side of headache. When these parameters were separately compared for gender, they were prolonged in boys during the attack in migraineurs; however in girls, while there was statistically significant difference at interpeak latencies of I-V, no significant difference was noted at peak latencies of wave V. CONCLUSIONS: ABR waves did not exceed clinical norms in migraine patients in headache-free period. But, important effects on sensorineural hearing parameters were detected during the attack. Our results indicated a transient impairment of the auditory brainstem function during the headache in pediatric migraine patients.

Adolescent↗

Tinnitus retraining therapy for patients with tinnitus and decreased sound tolerance.

Our experience has revealed the following: (1) TRT is applicable for all types of tinnitus, as well as for decreased sound tolerance, with significant improvement of tinnitus occurring in over 80% of the cases, and at least equal success rate for decreased sound tolerance. (2) TRT can provide cure for decreased sound tolerance. (3) TRT does not require frequent clinic visits and has no side effects; however, (4) Special training of health providers involved in this treatment is required for this treatment to be effective.

Acoustic Stimulation↗

A revised model of loudness perception applied to cochlear hearing loss.

We previously described a model for loudness perception for people with cochlear hearing loss. However, that model is incompatible with our most recent and most satisfactory model of loudness for normal hearing. Here, we describe a loudness model that is applicable to both normal and impaired hearing. In contrast to our earlier model for impaired hearing, the new model correctly predicts: (1) that a sound at absolute threshold has a small but finite loudness; (2) that, for levels very close to the absolute threshold, the rate of growth of loudness is similar for normal ears and ears with cochlear hearing loss; (3) the relation between monaural and binaural threshold and loudness; (4) recent measures of equal-loudness contours. Like the earlier model, the new model can account for the loudness recruitment and reduced loudness summation that are typically associated with cochlear hearing loss.

Cochlea↗

A study of electrical promontory stimulation in tinnitus patients.

Electrical promontory stimulation relieved tinnitus in 74 (57.4%) of 129 ears (112 patients). There was no significant difference in etiology of tinnitus, age, average audiogram, or tinnitus frequency between patients who responded to electrical stimulation and those who did not. Most patients who did not respond to the initial stimulation trial did not respond to the subsequent trials, suggesting that the initial response to treatment predicts the subsequent response. Patients who did not respond to repetitive treatment were supposed to be under severe stress.

Adolescent↗

[Therapy of tinnitus. Tympanic cavity infusion of lidocaine and steroid solution].

Tinnitus is an otological symptom which is often encountered and is yet difficult to treat. If tinnitus is of cochlear origin then it seems reasonable to assume that a total depression of the cochlear function will abolish cochlear tinnitus. To achieve this depression, transtympanic injections of a local anesthetic (4% Lidocaine) to anesthetize the inner ear and of Decadoron were conducted in a patient suffering from tinnitus. One hundred and sixty-eight patients (220 ears) who had suffered from relatively long-term tinnitus were included in this study. In almost all of the cases the clinical symptoms and the otological findings (i.e., the audiogram and caloric test) indicated that the probable lesion underlying the tinnitus was located within the end organ. In some cases this injection brought a transient (for few days), slight, neurosensorial deafness in the low-frequency range. This auditory disorder, however, was completely restored without sequelae. Our results are summarized as follows: in 76 ears, tinnitus was abolished completely, in 109 ears, tinnitus was considerably ameliorated, in 35 ears, tinnitus was slightly ameliorated or no effect. One hundred and nine patients (138 ears) who had suffered from tinnitus were included in this study. Decadoron was applied to the middle ear cavity by transtympanic injection. Our results are summarized as follows: in 87 ears, tinnitus was abolished, in 39 ears, tinnitus was considerably ameliorated, in 14 ears, tinnitus was slightly ameliorated or no effect.

Dexamethasone↗

Neuro-axonal recruitment: a result of selective compression.

Many acoustic neurinomas and CPA tumours present an audiometric picture of positive-recruitment hearing impairment although often the CMs are not significantly impaired (according to ECochG) and because, even in the case of a small acoustic neuroma, the interpeak latency between wave I and V (ERA) is increased in the majority of cases. Recruitment cannot be explained, in these cases, as an expression of an accompanying vascular inner ear lesion. Therefore, we attempt to interpret the differential audiometric picture to the various patterns of damage of the auditory nerve. The finding of tone decay is seen as an expression of myelin damage corresponding to the hearing loss in multiple sclerosis. The absence of any degree of tone decay excludes an isolated damage of the myelin sheaths; hearing loss then results from a disturbance also of the associated axons. At such a stage, where there is a functional loss to part of the neural fibres but with intact myelinated residual fibres, the result could be the phenomenon of recruitment for suprathreshold stimulation. This theory of selective compression is compared to an isolated efferent lesion theory as the cause for recruitment in AN and CPA tumours.

Audiometry↗

Sense, symbol, and soma: illness experience in the soundscape of everyday life.

This article explores the lived experience of women suffering from an illness prevalent in the Kui communities of Northeast Thailand. The symptoms, ranging from loss of appetite to chronic fatigue, were typically triggered by being exposed to certain kinds of sounds, such as motorcycles, quarrelling neighbors, or carousing drunkards. I examine the illness experience as it was constituted in the soundscape of everyday life to reveal how the meaning-endowed sounds aggravated the feeling of being vulnerable and defenseless. The felt immediacies created by the audio-somatic experience were reconceptualized within the indigenous somato-psychic framework as a form of illness. By examining the life histories and illness experiences of individuals who were rendered vulnerable and defenseless, the study reveals how symbols that carry political significance, the body as a cultural form of memory, and the senses combine to create a specific mode of being-in-the-world. Sense, symbols, and somatic processes combined to create an illness experience out of the felt immediacies of the Kui's socio-political predicament of marginality.

Acoustic Stimulation↗

Range and regression, loudness scales, and loudness processing: toward a context-bound psychophysics.

How does context affect basic processes of sensory integration and the implicit psychophysical scales that underlie those processes? Five experiments examined how stimulus range and response regression determine characteristics of (a) psychophysical scales for loudness and (b) 3 kinds of intensity summation: binaural loudness summation, summation of loudness between tones widely spaced in frequency, and temporal loudness summation. Context affected the overt loudness scales in that smaller power-function exponents characterized larger versus smaller range of stimulation and characterized magnitude estimation versus magnitude production. More important, however, context simultaneously affected the degree of loudness integration as measured in terms of matching stimulus levels. Thus, stimulus range and scaling procedure influence not only overt response scales, but measures of underlying intensity processing.

Attention↗

Measurements of loudness growth in 1/2-octave bands for children and adults with normal hearing.

The loudness growth in 1/2-octave bands (LGOB) procedure has been shown previously to provide valid estimates of loudness growth for adults with normal hearing and those with hearing loss (Allen, Hall, & Jeng, 1990), and it has been widely incorporated into fitting strategies for adult hearing aid users by a hearing aid manufacturer. Here, we applied a simple modification of LGOB to children and adults with normal hearing and then compared the loudness growth functions (as obtained from end-point data) between the two age groups. In addition, reliability data obtained within a single session and between test sessions were compared between the two groups. Large differences were observed in the means between the two groups for the lower boundary values, the upper boundary values, and the range between boundaries both within and across all frequencies. The data obtained from children also had greater variance than the adult data. In addition, there was more variability in the data across test sessions for children. Many test-retest differences for children exceeded 10 dB. Adult test-retest differences were generally less than 10 dB. Although the LGOB with the modifications used in this study may be used to measure loudness growth in children, its poor reliability with this age group may limit its clinical use for children with hearing loss. Additional work is needed to explore whether loudness growth measures can be adapted successfully to children and whether these measures contribute worthwhile information for fitting hearing aids to children.

Adult↗

Effect of slow-acting wide dynamic range compression on measures of intelligibility and ratings of speech quality in simulated-loss listeners.

The purpose of this study was twofold: (a) to determine the extent to which 4-channel, slow-acting wide dynamic range amplitude compression (WDRC) can counteract the perceptual effects of reduced auditory dynamic range and (b) to examine the relation between objective measures of speech intelligibility and categorical ratings of speech quality for sentences processed with slow-acting WDRC. Multiband expansion was used to simulate the effects of elevated thresholds and loudness recruitment in normal hearing listeners. While some previous studies have shown that WDRC can improve both speech intelligibility and quality, others have found no benefit. The current experiment shows that moderate amounts of compression can provide a small but significant improvement in speech intelligibility, relative to linear amplification, for simulated-loss listeners with small dynamic ranges (i.e., flat, moderate hearing loss). This benefit was found for speech at conversational levels, both in quiet and in a background of babble. Simulated-loss listeners with large dynamic ranges (i.e., sloping, mild-to-moderate hearing loss) did not show any improvement. Comparison of speech intelligibility scores and subjective ratings of intelligibility showed that listeners with simulated hearing loss could accurately judge the overall intelligibility of speech. However, in all listeners, ratings of pleasantness decreased as the compression ratio increased. These findings suggest that subjective measures of speech quality should be used in conjunction with either objective or subjective measures of speech intelligibility to ensure that participant-selected hearing aid parameters optimize both comfort and intelligibility.

Acoustic Stimulation↗

The determination of tinnitus loudness considering the effects of recruitment.

We have attempted to determine a meaningful measure of tinnitus loudness that considers loudness recruitment. Sixteen subjects with sensorineural tinnitus adjusted the level of a pure tone so that it was (a) at threshold, (b) equal in loudness to the tinnitus, and (c) uncomfortably loud. The pure-tone frequency was (a) at the frequency of the tinnitus pitch, and (b) at the octave frequency between 500 and 4000 Hz having the pure-tone threshold closest to 0 dB HL. In addition, the subjects adjusted the level of a broadband noise so that it (a) was at threshold, (b) just masked the tinnitus, and (c) was uncomfortably loud. These measurements were performed both in the ear ipsilateral and in the ear contralateral to the tinnitus. Formulae based on abnormal loudness functions and uncomfortable loudness levels are presented that convert equal-loudness matches in dB sensation level (SL) into loudness in sones. The level of broadband noise (in dB SL) required to mask tinnitus was about the same in the ipsilateral and in the contralateral ear for most of our subjects, regardless of the ear in which the tinnitus was localized. This noise level (in dB SL) required to mask the tinnitus correlated well with the level (in dB SL) of a tone at the most normal frequency judged equal in loudness to the tinnitus.

Adult↗