Sigfrid D. Soli
House Ear Inst., 2100 W. Third St., Los Angeles, CA 90057
Robert L. Goldberg
City of Los Angeles, 1401 W. Sixth Street, Los Angeles, CA 90017
Norms have been developed for the hearing in noise test [Nilsson et al., J. Acoust. Soc. Am. Suppl. 1 88, S175 (1990)]. Speech reception thresholds (SRTs) were measured adaptively in the presence of spectrally matched noise for 150 young male and female adults. Speech was presented at 0-deg azimuth in all conditions, and noise was presented at either 0-, 90-, or 270-deg azimuth at 65 dB(A). Pure-tone thresholds were measured at 0.5, 1, 2, 3, 4, 6, and 8 kHz. Subjects were also characterized according to their early language acquisition experience with English in one of five categories ranging from ``English only'' to ``no English in the home.'' Average SRTs for normal-hearing, ``English only'' subjects (pure-tone thresholds at all frequencies tested of 15 dB HL or better) noise equaled 62.26 dB(A) (-2.74 dB S/N). Several factors significantly influence thresholds: (1) spatial separation between the speech and noise lowered thresholds an average of 7.42 dB; (2) unilateral, high-frequency hearing loss elevated thresholds in quiet by 3 dB; and (3) thresholds in quiet and noise were elevated by 3.34 dB in subjects with normal hearing but ``no English in the home.'' This elevation of thresholds is especially intriguing because it suggests a cognitive/linguistic factor in the ability to understand speech in noise.