SOUND-EVOKED CHANGES IN BASILARY BLOOD-FL OW - A SHORT COMMUNICATION

In 55 volunteers with good hearing, sound-evoked changes in the blood flow of the basilar artery were studied using colour coded Doppler son ography. After a rest of twenty minutes 2 groups of subjects listened to sound of varying volume using a head phone. In one group (n = 25) t he sound volume was 25 dB and in the second group (n = 30) the volume was 65 dB. In both groups significant sound evoked changes of vascular resistance were found, quantified by the RI. In the case of applying soft sound (25 dB) the RI decreased, indicating an increase of volume flow while with louder sound (65 dB) the RI increased, indicating a re duction of flow.