Benefit of binaural hearing in a multi-source environment. II. Speech intelligibility.

Abstract

A multi-source listening environment was simulated under headphones by recording signals through KEMAR in a sound-deadened room. Seven loudspeakers were each positioned in the frontal plane 5 ft from KEMAR at 30-deg increments, ranging from +90 (right) to −90 (left). The recorded signals (IEEE Harvard sentences) were digitally mixed and played back under headphones in a sound-proof booth using a Digital Audio Tape (DAT) player. Speech intelligibility was measured for a ‘‘target’’ sentence in the presence of various ‘‘jammers.’’ Three variables were manipulated. First, the number of ‘‘jammers’’ was either none, one, two, or three. Second, the relative location of the targets and jammers was varied, such that they were either in close proximity, widely separated, or some of each. Third, the jammer content comprised of either other sentences, speech-shaped noise, babble or time-reversed sentences. Normal-hearing listeners were tested under binaural and monaural conditions. On each trial the location of the target sentence was known, and the percentage of key words correctly identified is reported. Speech intelligibility was degraded as the number of jammers and as the target proximity to the jammers was increased. [Work supported by NIH DC02696, DC00100-21.]