Determining binaural summation for stationary signals across the frequency spectrum

Abstract

The concept of binaural summation has been widely accepted; however, the value of summation, and the manner in which it is applied, is still under a great deal of debate. This research is an investigation of the binaural summation mechanisms through the use of a loudness comparison experiment for pure tones. Preliminary results have concluded that for pure tones presented at 40 dB the amount of summation increases with frequency from approximately 2 dB at 40 Hz up to 8 dB at 10 kHz. Due to the low hearing threshold at 40 dB, the experiment was modified such that the hearing threshold of each individual is collected in order to presented each signal at a fixed amplitude above the threshold of hearing for each frequency (i.e., a sensation level of 20 dB(SL)). However, similar outcomes have been found using this approach, thus supporting the conclusions that binaural summation does exist and is found to increase at defined increments with increasing frequency for pure tones. The eventual outcome of this work is to improve the existing loudness metrics to allow for the input of binaural measurements taken using binaural mannequins.