In-Head Localization of Acoustic Images

Abstract

Under certain conditions of acoustic stimulation, a listener may perceive a sound image that is localized within the head. Different authors have attributed such in-head localizations to (a) a static relationship between head position and components of the acoustic signal at the two ears, (b) abnormal acoustic-impedance loading of the middle ear, (c) independent (and, therefore, slightly different) transmission paths to the two ears, and (d) other causes generally applicable to the binaural-earphone listening situation. Experiments in free-field localization have shown that convincing in-head localizations can be demonstrated under circumstances that apparently do not involve the above factors to an important extent. In fact, there are numerous single- and multiple-transducer arrays that can give rise to complex in-head and external localizations. These are described and discussed in the light of relevant interaural signal parameters and present theories of in-head localizations.