Loudness-intensity relations under various levels of contralateral noise.

Abstract

This study investigated the effects of four levels of broad-band noise [40-, 60-, 80-, and 100-dB sensation level (SL)], presented to the contralateral ear, on the loudness of a monaurally presented 1000-Hz pure tone. Loudness functions were obtained with the method of numerical magnitude balance. The findings indicate that when monaural loudness functions for a 1000-Hz pure tone, obtained with contralateral noise present, are compared with monaural loudness functions for a 1000-Hz pure tone, presented in quiet, there is a loss of loudness at low sensation levels, a loudness increase of as much as threefold at moderate SLs, and approximately equal loudness at high SLs. The loudness at lower SLs appears to be inversely related to the intensity of the broad-band contralateral noise, and the loudness at moderate SLs appears to be directly related to the intensity of the broad-band contralateral noise.