What is binaural audio?

The binaural recording technique records the sound that falls into the ears in the same way as it is perceived by the human hearing organ. The sound signals obtained in this way are reproduced using headphones. In this way, external influences on the sound are eliminated. The recording can use an dummy head or even a torso with different details or use the sound engineer’s own head. The sound engineer can move during the recording. The dummy head microphone, on the other hand, is usually kept stationary.
In this way a remarkable realism can be achieved. This, however, is limited by the restriction of head movement and the enclosing effect of headphones. The happy listener therefore gets a good match and impressive realism.

What is the difference between binaural audio and stereo?

Stereo

In general, stereo sound recordings are mixed exclusively using loudspeaker systems during listening; hence the name “loudspeaker stereo”. The properties used by humans for localization, such as the shape of the head or ear, are rightly not taken into account, because in natural hearing and in reproduction via stereo speakers, the ear forms the aural signals itself.

On a regular stereo system with speakers (not headphones), the listener’s left ear will hear both speakers and the right ear will hear both speakers too. If the left ear hears only the left speaker and the right ear hears only the right speaker, there is no crosstalk. In other words, crosstalk occurs when the left ear also hears the right speaker and the right ear also hears the left speaker. So when a listener hears a stereo signal through headphones, there is no crosstalk and the left and right channels are completely separated. Thus, the intended listening experience of a sound engineer mixing with speakers will differ significantly due to the lack of crosstalk when listening through headphones. The sound sources are lateralised and there is typically a loss of energy in the centre of the sound image compared to the loudspeaker reproduction of the same recording. The localization is therefore considerably limited. The sound sources reproduced in this way are localized in the middle of the head.

Binaural

The term “binaural” is unfortunately still confused with stereo because it also consists of two audio channels.

However, in contrast to stereo playback via headphones, binaural signals contain the crosstalk of sound signals described above. These are embedded spatial indications in the form of time, intensity and spectral coloration. These signals imitate and improve natural human localization. The target reproduction system for binaural signals is primarily headphones. When properly recorded, synthesized and reproduced, binaural signals produce a convincing impression of spatial sounds as they occur in the natural listening environment.