40 Hz Pure Tone | Very Low Frequency Deep Bass | 9 Hours Black Screen

9 hours of a pure, very low frequency bass tone at 40 Hz. This is towards the bottom of the range of human hearing and may not be audible through the speakers of some devices. CAUTION: this frequency may damage speakers and headphones if played too loud!

#brainwaveentrainment #40hz #gamma #deepbass #blackscreen #gammawaves #focus