- Alex U. Case
Form factors for loudspeakers designed for proximity to the ear. Ear buds and in-ear headphones are inserted into the ear canal, circum-aural headphones fit over the entire outer ear, and supra-aural headphones are placed against the outer ear. The addition of a microphone near the mouth produces a headset useful for two-way communication.
Two important implications of the closeness of the loudspeaker drivers to the ears are binaural listening and electro-acoustic efficiency. Binaural listening, in which each ear receives a dedicated signal without inter-aural crosstalk and devoid of the acoustic signature of the actual listening space, is essential to some forms of audio research and opens the door to the creation of new perceived environments through a range of signal processing techniques focused on the localization and spatialization of sound. Headphones need only a small fraction of the sound power required by traditional loudspeaker enclosures placed at a distance, and this efficiency is crucial for the portability of battery-powered devices....