The simplest binaural setup is very similar to a basic stereo microphone recording. In the simplest stereo microphone setup, two mics are placed in front of a sound stage, with the distance between the mics equal to between one-third and one-half the size of the sound stage. This creates the feeling of sounds coming from different positions in front of the viewer, but does not create the vivid, three-dimensional feel of binaural recording. In a basic binaural setup, the microphones are moved closer together--about 165 millimeters apart. A baffle such as a Jecklin disc is put between them. A Jecklin disc is a disc of material made to absorb sounds. Sounds coming from the side are absorbed more completely than sounds coming from in front or behind. Higher-frequency sounds are absorbed more than lower frequencies. These effects mimic the acoustic effects of a human head. When the listener hears the recording on headphones, it sounds very much like he is actually there, hearing the sounds from the directions from which they are actually coming.
The human head shapes sound in complicated ways. Sounds coming from the left, for example, can wrap around the head, arriving at the right ear with slight delays and distortions. The shape of the inner and outer ear also effects sound, altering the timbre, delay and attenuation of sounds from different directions in different ways. A dummy head uses a model head to create truer binaural sound than a baffled stereo microphone. The head is shaped like a real human head, with microphones in the ear drums, picking up sounds in the same way a person normally would hear them. Different people have different shaped heads, so a single dummy head will not create perfect binaural recording for everyone, but dummies do create a more nuanced recording than baffled stereo.
In-ear microphones offer some of the truest binaural recordings. The recorder places a small microphone in each of his ears and links the microphones to a digital recorder. The microphones not only capture the acoustic effects of his head, but also capture the effects of his torso and limbs in dampening the sound. The in-ear microphone also allows the recorder to easily move the mics anywhere she wants simply by walking there. The main drawback to this technique is obvious: For most types of recordings, the mic wearer would have to stand perfectly still for a long time to record several takes.