![]() Normally, such a noise would be expected to yield damage at a more apical region of the cochlea. It was previously noted that the high-frequency or basal turn of the cochlea was particularly vulnerable to the combined effects of acrylonitrile and noise when the octave band noise (OBN) was centered at 8 kHz. Acrylonitrile depletes glutathione levels while noise can increase the formation of reactive oxygen species. ![]() The mechanism by which acrylonitrile promotes NIHL includes oxidative stress as antioxidant drugs can partially protect the cochlea from acrylonitrile + noise. Teresa Colomina Fosch Exposure to acrylonitrile, a high-production industrial chemical, can promote noise-induced hearing loss (NIHL) in the rat even though this agent does not itself produce permanent hearing loss. However, the determination of PTCs is probably too time-consuming to be used for routine diagnosis of dead regions in clinical practice (4) The measurement of detection thresholds for pure tones in TEN provides a simple method for clinical diagnosis of dead ![]() The main conclusions are: (1) Dead regions may be relatively common in people with moderate-to-severe sensorineural hearing loss (2) Dead regions cannot be reliably diagnosed from the audiogram (3) PTCs provide a useful way of detecting dead regions and defining their boundaries. This paper reviews the following topics: the effect of dead regions on the audiogram methods for the detection and delineation of dead regions based on psychophys-ical tuning curves (PTCs) and on the measurement of thresholds for pure tones in 'threshold equalizing noise ' (TEN) effects of dead regions on speech perception effects of dead regions on the perception of tones implications of dead regions for fitting hearing aids. The region can be defined in terms of the range of characteristic frequencies (CFs) of the IHCs and/or neurons immediately adjacent to the dead region. Sometimes there may be complete loss of function of inner hair cells (IHCs) over a certain region of the cochlea this is called a 'dead region'. Hearing impairment is often associated with damage to the hair cells in the cochlea.
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