Loudness matching of 40 Hz pulse and amplitude-modulated sounds for gamma wave entrainment in brain

Abstract

Extensive research has explored the treatment or suppression of dementia through the presentation of sensory stimuli, such as pulse sounds with a repetition frequency of 40 Hz or amplitude-modulated sounds at 40 Hz, which evoke or entrain gamma waves. Empirical evidence indicates that, even when the equivalent noise level is adjusted, there is significant deviation in perceived loudness. This study measured the loudness of pulsed and modulated sounds using the constant method. The results showed that the modulated wave required no adjustment, while the sinusoidal and rectangular pulses required adjustments of −13 dB and −21 dB in addition to the equalization of their equivalent noise levels, respectively.