Effect of loud sound exposure on the cochlear blood flow.

The effect of loud sound exposure on cochlear blood flow was studied in the guinea pig by the laser Doppler method. Fourteen guinea pigs with normal Preyer reflex were anesthetized and tracheotomy was performed. A tracheotomy tube was connected to a ventilator and the experiment was performed with artificial ventilation. After exposure of the tympanic bulla and complete removal of the mucosa, a probe of a laser Doppler flowmeter was attached to the lateral wall of the basal turn of the cochlea. A specially-designed ear piece connected with a speaker was inserted into the external ear canal and loud sound (10 kHz at 120 dB SPL) was delivered to the ear for 30 min. Thirteen of the 14 exposed guinea pigs showed a prompt decrease in cochlear blood flow at the onset of the sound exposure and 12 of the 13 guinea pigs showed a prompt recovery of the cochlear blood flow after the cessation of the sound exposure.