Basal turn cochlear lesions following exposure to low frequency noise

Ossicular removal gives good protection from injury to noise exposed ears, at least 28 dB when assessed by anatomic techniques. The surgical procedure used for ossicular removal is a simple and effective method of producing an internal control ear. Such an internal control should prove to be valuable for a variety of studies in which behavioral anatomic, or biochemical data are to be collected. Exposure to an octave band of noise centered at 0.5 kHz at a high intensity level causes cell damage at the basal end of the cochlea, in addition to damage in the third turn which is equivalent to that found in animals exposed at a lower intensity. The damage at the basal end is significant and is found at approximately the same locus as the damage present in animals exposed to an octave band of noise centered at 4.0 kHz. The authors cannot attempt to explain the reasons for the damage in the 4.0 kHz region until further studies are completed.