In chapter 8 we discuss the concept of beat frequencies, and their involvement in consonance and dissonance perception. There have been a number of suggestions made--and marketing that followed--that suggests that perceiving these beat frequencies binaurally , i.e., one tone in each ear, has tremendous therapeutic effects. Here's some research that disputes those findings: https://www.inverse.com/mind-body/the-science-of-binaural-beats-why-it-may-be-bunk, and the scholarly article here: https://www.eneuro.org/content/early/2020/02/07/ENEURO.0232-19.2020. What is interesting about the research, however, is the verification that the additional frequencies generated in the beating phenomenon, whether binaural or mono, do indeed, entrain brainwaves. What is less certain, is the effect this entrainment has on us.