Binaural recording and reproduction.

Binaural literally means "having or relating to two ears." Binaural hearing, along with frequency cues, lets humans and other animals determine direction of origin of sounds.



Binaural recording

Binaural recording is a method of recording audio which uses a special microphone arrangement. Dummy head recording refers to a specific method of capturing the audio, generally using a bust.
The term "binaural" has often been confused as a synonym for the word "stereo", and this is partially due to a large amount of misuse in the mid-1950s by the recording industry, as a marketing buzzword. Conventional stereo recordings do not factor in natural crossfeed or sonic shaping of the head and ear, since these things happen naturally as a person listens, generating their own ITDs (interaural time differences) and ILDs (interaural level differences).



Recording technique



With a simple recording method, two microphones are placed seven inches (18cm) apart facing away from each other. This method will not create a real binaural recording. The distance and placement roughly approximates the position of an average human's ear canals, but that is not all that is needed. More elaborate techniques exist in pre-packaged forms. A typical binaural recording unit has two high-fidelity microphones mounted in a dummy head, inset in ear-shaped molds to fully capture all of the audio frequency adjustments (known as head-related transfer functions (HRTFs) in the psychoacoustic research community) that happen naturally as sound wraps around the human head and is "shaped" by the form of the outer and inner ear. The Neumann KU-81, and KU-100 are the most commonly used binaural packages. The KEMAR system is another alternative. The HEAD acoustics aachenhead unit does automatic equalization and processing to create a more enveloping experience. Other alternatives are the B&K[1] and the 01dB-Metravib[2] acoustic heads. The last one following exactly the IEC959 standard. A simplified version of this, called a Jecklin Disk, used a 30 cm (11.81") acoustically-absorptive disk between the mics, as a compromise. Now the new Disk is 35 cm in diameter and has a spacing of the microphones of 36 cm.[3]
Binaural "in-ear" microphones can be linked to a portable Digital Audio Tape (DAT) or MiniDisc recorder, bypassing the need for a dummy head by using the recordist's own head.



Playback



Once recorded, the binaural effect can be reproduced only using headphones. It does not work with mono playback; nor does it work while using loudspeaker units, as the acoustics of this arrangement distort the channel separation via natural crossfeed (an approximation can be obtained if the listening environment is carefully designed by employing expensive crossfeed cancellation equipment.)
The result is a listening experience that spatially transcends normally recorded stereo, since it accurately reproduces the effect of hearing a sound in person, given the 360° nature of how human ears pick up nuance in the sound waves. Binaural recordings can very convincingly reproduce location of sound behind, ahead, above, or wherever else the sound actually came from during recording.



Sample



Virtual barbershop

link1: http://media.noob.us/virtualbarbershop.mp3