In essence Binaural recording is a stereo recording technique that differs from all the others in that it has to be played back through headphones as opposed to speakers. Binaural recordings can be some of the most realistic recordings spatially, but only when played back on headphones and usually if played back on speakers, the stereo imaging can be quite poor. This is because the headphones ensure that each ear only hears what was recorded by the microphone on that side of the head, whereas speakers produce crosstalk so that some of the sound from the left speaker can be heard by the right ear, and vice versa, muddying the spatial imaging. Binaural recordings are made using a pair of microphones spaced about 6 inches apart so as to imitate the human ears but crucially with a baffle in between them to emulate the head and dummy heads (models of a human head with mics fixed to, or inside) are available from some high end suppliers such as Neumann. However these dummy heads can be very expensive (The Neumann K100 Binaural Head costs £5,500) so most sound engineers use their own head, and either attach mics near their ears such as on a pair of glasses, or in some cases tape them inside their ears. However perfectly good results can be obtained by spacing two mics 6" apart and putting a sound-absorbing baffle like a rolled-up towel between them to emulate the head. The spacing of the mics, and the 'sound shadow' cast by the head, produce auditory cues that the brain decodes into spatial information that can be uncannily accurate and a recording played back in the same room as it was recorded in, can be very scary! If someone speaks behind the head on the recording, for instance, the listener will usually turn to answer someone who's no longer there!