Speech Intelligibility by Head Contact as Function of Location on Head

Abstract

A study was made to determine the level, spectrum, and intelligibility of speech available for contact transducers, as a function of head location. A specially designed head-contact microphone was developed for use in these tests. The output of the head-contact microphone and that of a “flat” acoustical microphone were simultaneously recorded for 10 talkers reciting phonetically-balanced test sentences. The recorded data were then played back, and trained listeners subjectively evaluated the intelligibility of the contact speech versus the acoustically received speech. Several head areas showed highly intelligible speech with good consonantal pickup, while other regions were notably poor even when equalization techniques were employed. Spectral analysis showed that regions that had adequate high-frequency energy generally corresponded to those that had exhibited good intelligibility in the listening tests. The head was grouped into four regions—forehead, ear, cheek, and top and back of head. The over-all intelligibility of each area was evaluated. The forehead region gave the most desirable output for contact pickup. Over-all output level available at each area was measured and a statistical analysis showed only modest level differences for most regions of the head. [Work supported by the U. S. Army Electronics Command.]