Effect of training in sound localization in the median plane

It has been reported that monaural subjects can localize the sound image correctly [L.B.W. Jongkees, Acta OtoLaryngologica 465 (1957)]. It is supposed that training is an important factor in localization. The purpose of this investigation is to determine the effect of training on localization in the median plane. When normally binaural subjects are made monaural by occluding one of the ears, the localization errors increase at the beginning and decrease after temporary training. In this case, subjects can localize the sound image by discriminating the timbre according to the head-related transfer function depending on the direction. Also, it is found that binaural and permanently monaural subjects can localize the sound image correctly even at the first test. It is considered that monaural subjects have the possibility of correct sound localization as the same process of language recognition, and that the localization of binaural subjects is caused by a resultant from long training by the small interaural difference in the median plane as an easier process.