Similarity of Traveling-Wave Delays in the Hearing Organs of Humans and Other Tetrapods

Transduction of sound in mammalian ears is mediated by basilar-membrane waves exhibiting delays that increase systematically with distance from the cochlear base. Most contemporary accounts of such “traveling-wave” delays in humans have ignored postmortem basilar-membrane measurements in favor of indirect in vivo estimates derived from brainstem-evoked responses, compound action potentials, and otoacoustic emissions. Here, we show that those indirect delay estimates are either flawed or inadequately calibrated. In particular, we argue against assertions based on indirect estimates that basilar-membrane delays are much longer in humans than in experimental animals. We also estimate in vivo basilar-membrane delays in humans by correcting postmortem measurements in humans according to the effects of death on basilar-membrane vibrations in other mammalian species. The estimated in vivo basilar-membrane delays in humans are similar to delays in the hearing organs of other tetrapods, including those in which basilar membranes do not sustain traveling waves or that lack basilar membranes altogether

Critical learning period for speech acquisition and screening techniques in early detection of hearing impairment

In order to develop verbal communication skills, an infant nervous system needs sound stimuli, especially human speech, in the early and critical learning period of life. The maturation of hearing and language learning abilites of an infant is considered to be complete within the first two to three years of life. Therefore, detection of hearing impairment before the end of the critical language learning period is considered crucial if a child is expected to acquire his/her native language properly. Parents or caregivers may suspect the presence of a delay in language acquisition; however, relying only on parental awareness could cause a delay in detection of the hearing impairment. Even mild hearing loss may interfere with normal development of speech and language in infants, therefore, universal screening of infants for hearing loss as early as possible should be the goal

Measures of cochlear travelling wave delay in humans: I. Comparison of three techniques in subjects with normal hearing

This study was designed to estimate and compare measures of cochlear travelling wave delay and travelling wave velocity in normally-hearing adults. Travelling wave delay and velocity measures were estimated in 23 normally-hearing adults using three different test techniques: ii derived auditory brainstem responses (ABR) iii derived frecluency-following responses (FFR. and iii) tone-burst-evoked otoacoustic emissions TBEOAE. Estimates, from ABR and BEOAE were comparable to each other in terms of both averaged group values and associated standard deviations. Furthermore. mean cochlear travelling wave velocity estimated from ABR and TBEOAE were comparable to published estimates, Average cochlear delays obtained using the derived FFR were significantly shorter than those obtained from the other two techniques. possibly due to the effect of cochlear microphonic contamination. Among the dependent variables investigated, measures of delay are to be preferred over velocity since the latter are based on uncertain values of cochlear distance

Unusual regression of a sudden-onset sensorineural hearing loss in a patient with cerebellopontine angle pathology

This is a report of a patient with small internal acoustic canal pathology presenting as a sudden-onset sensorineural hearing loss. Initially the patient received non-specific empirical medical therapy and the sudden-onset sensorineural hearing loss recovered rapidly. Regression of the hearing loss, despite no change in magnetic resonance imaging (MRI) findings after the medical treatment is documented and discussed

Effects of a single session of hemodialysis on hearing abilities

A prospective study was designed to evaluate the effects of a single session of hemodialysis on the parameters of hearing. We carried out serial audiological tests (tympanometry, pure-tone, speech and high frequency audiometry) in 19 patients with chronic renal failure undergoing hemodialysis. Tests were performed on patients 1 h before and 2 and 24 h after a randomly selected session of hemodialysis. The results of audiological tests indicated no significant adverse effect of a single session of hemodialysis on hearing