Effect of a Background Noise on the Loudness Function at 1000 cps

Abstract

Only a few studies have been concerned with the measurement of the loudness of a 1000-cps tone in the presence of noise; and there is a considerable discrepancy among the results, especially at low sound intensities. The discrepancy appears to be due to biases in procedures. In order to determine the form of the masked-loudness function, a series of experiments, which were designed to reduce the biases to a minimum, was performed. It has been found that, by decreasing the procedural biases and by obtaining measurements under similar experimental conditions, the average of magnitude estimation and magnitude production can be used to corroborate the results of loudness matching. By combining the loudness-matching field with the one determined by magnitude estimation and magnitude production, the best estimate of the masked-loudness function is obtained. Two loudness curves are constructed, one for a 40-dB threshold shift and the other for a threshold shift of 60 dB. The form of these curves is in good agreement with the results of other investigations in which balanced procedures are followed. The theoretical implications of these data are examined. (Work supported by a contract between the U. S. Office of Naval Research and Syracuse University.)