Directional Audiometry: II. The Influence of Azimuth on the Perception of Speech

Abstract

In 30 persons with normal hearing, a previously described apparatus (Tonning, 1970) was used for free field determinations of the intelligibility of speech in relation to the azimuth of the source: Directional Threshold of Intelligibility (DTI) was recorded both with and without background noise. Two loudspeakers, the one producing speech and the other producing white noise, could be rotated independently in the horizontal plane around the test person, permitting an analysis of the dependency of the DTI upon the positions of the speech and the noise source. The assumption is made that DTI is dependant on age. With the help of electronic computer analysis the material collected during the examinations was used to construct a standard diagram showing the DTI values in persons with normal hearing, with and without background noise.