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→Binaural Audio
You might have already heard about mono and stereo sound systems. Mono recordings only use one microphone and both of your speakers would be playing out the same soundtrack. Stereo recordings on the other hand use two separate microphones at a distance from each other, one meant for your left speaker or earphone to play, while the other records audio for your right ear.
The method for recording and reproducing 3D audio, also known as binaural audio, goes back to the late 19th century.<ref name="theverge">http://www.theverge.com/2015/2/12/8021733/3d-audio-3dio-binaural-immersive-vr-sound-times-square-new-york</ref> The simplest form of binaural recording requires two microphones placed roughly in the same distance as is the average position of human ears. In another method, both of the microphones are placed inside ear-shaped bodies at an optimum distance from one another as well as the source of the audio. It allows the recording to mimic real life sounds. There are, of course, many additional factors that have to be considered in order to produce a high-quality recording. Some One of these include the shape of the outer and inner ear, the so-called head shadow, or a proper frequency response compensation in the playback device.
The playback device is of special significance since binaural audio requires headphones or a distinct stereo setup to work properly. Regular speakers exhibit various degrees of so-called crosstalk, which means that sound from speaker A mixes with sound from speaker B and cancels the binaural effect out. Speakers need to be placed closely together at 10-30 degrees for crosstalk to be minimized. Headphones do not have this problem and the only real requirement is a proper sound isolation. An open design shows slightly better acoustic properties for binaural audio, but this is actually quite negligible when we consider just how big differences in anatomy can be found, for example, just between males and females. A single pair of headphones simply cannot fit perfectly on everybody. The good news is that this is not really a problem because the effect is very convincing even with just an average pair of earbuds or headphones.
