Dependence of binaural loudness summation on interaural level difference and frequency for pure tones

Most of the existing loudness models are based on the diotic listening hypothesis, though human beings always hear in dichotic listening conditions. In this situation, the arithmetic mean of loudness at both ears is usually taken as the approximate value of overall perceived loudness, unaffected by the interaural level difference (ILD). The present work investigated the overall perceived loudness for pure tones in dichotic listening conditions through a subjective experiment. Two experimental procedures and systematic errors were investigated to prove the accuracy of the subjective test. The results showed that fluctuation was insignificant in the low frequency range, while apparent fluctuation of overall loudness could be observed at a high frequency. The overall loudness deviated from the arithmetic mean value as the ILD became larger. A revised model for overall loudness in dichotic listening conditions was proposed. The proposed model and experiment are consistent.