A Study of Talking Distance and Related Parameters in Hands-Free Telephony

Abstract

This paper outlines the problems of providing satisfactory hands-free operation of the telephone and discusses various methods which can be applied to their solution. Particular attention is given to acoustic environment, proximity talking (as applied to hands-free operation of the telephone) and voice switching. Preference indications were obtained for 18 subjects in 18 different locations for proximity and distant talking without voice switching, and for the same number of subjects and locations for proximity and distant talking with voice switching. In the lotter tests, supplementary data were also obtained without voice switching. Regardless of the type of circuitry, the preference decision was considerably affected by the amount of reverberation at the hands-free location; proximity operation was generally favored under conditions of moderate to high reverberation, nonproximity operation under conditions of low reverberation (high room constant). Other factors which affected the preference for hands-free proximity and distant talking are discussed.