A binaural beat is an auditory illusion perceived when two different pure-tone sine waves, both with frequencies lower than 1500 Hz, with less than a 40 Hz difference between them, are presented to a listener dichotically (one through each ear). For example, if a 530 Hz pure tone is presented to a subject's right ear, while a 520 Hz pure tone is presented to the subject's left ear, the listener will perceive the auditory illusion of a third tone, in addition to the two pure-tones presented to each ear. The third sound is called a binaural beat, and in this example would have a perceived pitch correlating to a frequency of 10 Hz, that being the difference between the 530 Hz and 520 Hz pure tones presented to each ear.
I used to listen to an awesome series of audio tracks of this stuff and it was really trippy. It was easy to float away into some different world whilst listening to the properly produced tracks that were designed and tested, to do exactly that. One night I fell asleep with this stuff still playing through my ear buds for hours. I had such an intense dream/nightmare and then when I finally woke up in a sweat, this shit was playing in my ears.
Now this stuff is all over youtube, and there's ones that attempt to simulate a DMT trip, LSD and Shrooms.
I have listened to them all and they do not make me trip but they do have a noticeable effect. If you lay down or lay back in a chair and listen to this stuff whilst relaxing then it definitely has a calming effect and I often doze off, but I can't say that I hallucinate or talk to entities or any shit like that.