Sphere stereo

This is a stereo miking technique based on simulating the acoustic field around the human head. An 8-inch solid sphere separates two omnidirectional microphones, which are placed diagonally with their diaphragms flush with the surface of the sphere. The idea is to emulate the basic interaural proportions of a human head i.e., the head shadow effect and interaural time difference (ITD). Usually, head-related stereo techniques use directional microphones, but since sphere stereo uses omnidirectional microphones, this technique can also be used as main stereo pair at larger distances without loss of low frequencies. But the rather large solid sphere will act as an acoustic equalizer, which will color the higher frequencies rather significantly. The sphere will not only cause a boost of higher frequencies, but will also introduce significant ripples on the frequency response.