Monaural beats are used for brainwave entrainment in which two tones which would be used binaural beats

Binaural beats

Binaural beats or binaural tones are auditory processing artifacts, or apparent sounds, the perception of which arises in the brain for specific physical stimuli...

 are played in each channel resulting in a stronger stimulus. With monaural beats, the interference pattern that produces the beat is outside the brain so headphones are not required. They differ from isochronic tones

Isochronic tones

Isochronic tones are regular beats of a single tone used for brainwave entrainment. Similar to monaural beats, the interference pattern that produces the beat is outside the brain so headphones are not required for entrainment to be effective. They differ from monaural beats, which are constant...

because monaural beats are a sine wave pulse rather than entirely separate pulses of a single tone.