Monaural beats vs. binaural beats: what's the difference?

Binaural beats play two slightly different tones, one per ear; your brain perceives a “phantom” third beat between them that only exists in your head, and only works through headphones. Monaural beats mix those same two tones into one track before it reaches your ear, so the beat is physically present in the audio itself.

FMB uses monaural beats, plus isochronic beats (a single tone switching on and off at a set rate). All three approaches aim at the same mechanism — brainwave entrainment via the auditory steady-state response (ASSR) — but the beat reaches the ear differently, and the published support differs too. See “Do binaural beats work?”