Effects of Electroacoustic Characteristics of Hearing Aids on Speech Understanding

Research under this contract is broadly concerned with the relationship between the electroacoustic characteristics of hearing aids and their successful use by the hearing-impaired. We seek the elusive link between the physical and the behavioral: the extent to which differences in electroacoustic factors affect the listener's ability to understand speech through the aid. The present report is specifically concerned with the relationship between speech understanding and the electroacoustic parameters of frequency response, effective bandwidth, and harmonic distortion in a sample of 21 commercially available hearing aids. The overall design was to obtain a representative sample of commercially available aids and derive measures of physical performance. Speech intelligibility test materials were then recorded through each aid and the resulting tapes used to test various groups of listeners. Detailed correlational analyses were carried out between behavioral test results and the various electroacoustic indices of hearing-aid performance. Subsequent sections describe, in detail, the sample of hearing aids, the procedures used to measure speech understanding, and correlations between electroacoustic measurements and psychoacoustic performance data for both normal and hearing-impaired listeners.