binaural sound (binaural beats)
Binaural sound is stereo audio that is recorded through a dual microphone setup. The goal of recording binaural sound is to create a 3D audio effect that simulates sound as if it is being heard live. Binaural sound is best experienced by headphones. The word binaural literally means "having two ears."
Binaural sound has been used to create more life-like listening experiences in music and entertainment since its creation in the 1930’s. The way binaural sound is recorded requires the placement of two microphones at a distance apart, equal to the distance between the ears on a human head. Binaural sound creates a layered user experience because it allows the location of one sound to be distinguished from the location of another sound. This is because when sound arrives in one ear sooner than the other, the approximate location of a sound's origin can be recognized by the brain and directional sound can be distinguished.
Binaural beats and ASMRs
In healthcare, binaural sound is used in self-hypnosis and biofeedback activities to induce specific brainwave states. In 1839, Prussian physicist and meteorologist Heinrich Wilhelm Dove discovered that when two tones of different frequencies are sent simultaneously to the left and right ears, the brain perceives a third tone that represents the mathematical difference between the first two frequencies. The called phenomenonis known as entrainment and the third tone is known as a binaural beat.
For example, when a 300 Hz sound frequency is sent to the left ear, and a 295 Hz frequency is stent to the right ear, the brain will process those two frequencies and perceive a new frequency at 5 Hz. Researchers suggest that listening to low-tone frequencies can slow down brain-wave activity, help the listener relax and even relieve pain for some individuals.
Binaural beats are sometimes used in virtual reality and augmented reality games to elicit an autonomic sensory meridian response (ASMR) in the player. In this use case, binaural beats might be used to send shivers down the player's spine and create a more interactive playing experience.