Cochlear blood flow. The effect of noise at 60 minutes' exposure.

The effect of 60 minutes of exposure to high-frequency (10- to 40-kHz), high-intensity (115-dB) noise on the cochlear blood flow (CoBF) was investigated in adult gerbils. The CoBF was measured with a newly improved microsphere method. The number of microspheres in cochlear tissue that had been dissected by the surface preparation technique was assessed by direct counting. Our experiments have indicated that the CoBF is elevated even after 60 minutes of noise exposure. This was true particularly in the areas where these frequencies stimulate the cochlea. The noise also increased CoBF in the opposite ear in areas not corresponding to the stimulation frequencies (second and third turn). This phenomenon is under further investigation.