Detection of new acoustic signals from the human head

Abstract

New acoustic signals generated in the human head have been found using piezoelectric transducers of longitudinal acoustic oscillations; these signals clearly manifest themselves in recording from the temporal regions and are less pronounced when recording from the forehead. They have a form of 4-ms pulses with a repetition frequency varying from 60 to 120 ms. The signal level exceeds that of thermal acoustic fluctuations by about two orders of magnitude. The signals are formed when the subject of an experiment is relaxed; i.e., the human is at rest with closed eyes and is about to fall asleep. The repetition frequency of these signals is close to the alpha-rhythm frequencies; however, there is no exact correlation between these types of signals at long (of about minute) time intervals. The signals recorded from different temples generally have no strong synchronization. Since some parameters of these signals are close to those of electroencephalographic signals, the former can be referred to as acoustoencephalographic signals.