Contribution of acoustical characteristics to auditory perception of silent object

Not only the visually-impaired people but also the sighted people can aurally perceive the existence or the some characteristics of a silent object. However, the phenomenon or mechanism of this ability is as yet unclear. In this paper, acoustical transfer functions (ATFs) from a sound source to the ears were measured in the existence or non-existence conditions of a silent object at several locations, using dummy-head microphones. Then, sound stimuli generated by convolution of ATFs to pink noise were presented binaurally to participants and then the sound differences of the stimuli were discriminated. Next, contribution ratios of some acoustical differences to discrimination result were analyzed by means of regression analysis. The results indicated that spectral ripple caused by the interference between background and reflected sounds mainly contributed to the auditory perception of silent object.