Most Comfortable Loudness for Pure Tones and Speech in the Presence of Masking Noise

Abstract

Pure-tone and speech most-comfortable-loudness (MCL) levels were determined in noise and quiet. A Bekesy-type tracking task was used to determine the MCLs under all conditions. The subjects (N = 12) tracked their MCLs for five frequencies (250, 500, 1000, 20008, and 4000 Hz) in the presence of four white-noise levels (55, 65, 75, and 85 dB SPL) and in quiet. Speech MCLs were tracked under the identical noise conditions. The results indicated that the mean MCLs for tones between 500 and 4000 Hz, and for the speech stimuli, systematically increased as a function of the masking level. The rate of this increase was 7 dB per 10-dB noise increment for both stimulus modes when the level of the noise exceeded 65 dB SPL. At levels below 65 dB SPL, however, pure-tone MCL increases were only about 3 dB per 10-dB noise increment, while the slope of the speech MCL function remained relatively unchanged. The variability of MCL judgments for both stimulus modes decreased as a function of increased masking.