Previous sound effects on loudness in paired comparison experiments

Abstract

In this study, we investigated the effects of a previous sound on loudness by performing paired comparison experiments. Two pure tones measuring 74 to 86 dB SPL at 500 Hz were presented monaurally at a certain interstimulus interval (ISI), which was set between 0.5 and 8 s. One of the pure tones was presented in one ear, and then the other was presented in the contralateral or ipsilateral ear. The subject compared the loudness of two pure tones and responded which sound was felt louder. The effect of presentation order in the paired comparison was calculated from the experimental results, and then the previous sound effect was obtained from the presentation order effect. As results, the sound presented second in the ipsilateral ear was perceived to be about 1 dB softer than the first sound at an ISI of 0.5 s even when both sounds had the same SPL. On the contrary, the second sound in the contralateral ear was perceived to be about 1 dB louder than the first sound significantly. This effect is referred to as “auditory reinforcement.” The effect level of auditory reinforcement decreased as ISI increased.