A binaural beat is an auditory illusion that occurs when each ear is listening to a tone that is slightly different from the other ear. It is theorized that listening to binaural beats increases brain activity in the frequency range corresponding to the frequency of beats presented. Hence, individuals listen to binaural beats intending to entrain their brains to experience a specific mental state.

There has been relatively little research on how binaural beats affect heart rate variability, or the variation of time between heart beats. Heart rate variability is associated with heart health. In this thesis we present an application called SoundSlug, which generates binaural beats and records heart rate data. We conducted a study using SoundSlug where we presented 31 research participants with two binaural beat frequencies and a control condition with no binaural beats. Findings suggest that binaural beat conditions do not affect heart rate variability significantly from the condition with no beats. However, all audio conditions trended toward lower heart rate variability than the baseline silence.