Evidence of Lateralization Cues in Grand and Upright Piano Sounds

In a previous experiment we have measured the subjective perception of auditory lateralization in listeners who were exposed to binaural piano tone reproductions, under different conditions (normal and reversed-channel listening, manual or automatic tone production by a Disklavier, and disclosure or hiding of the same keys when they were autonomously moving during the automatic production of a tone.) This way, participants were engaged in a localization task under conditions also involving visual as well as proprioceptive (that is, relative to the position and muscular effort of their body parts) identification of the audio source with the moving key, even when the binaural feed-back was reversed. Their answers, however, were clustered on a limited region of the keyboard when the channels were not reversed. The same region became especially narrow if the channels were reversed. In this paper we report about an acoustic analysis of the localization cues conducted on the stimuli that have been used in the aforementioned experiment. This new analysis employs a computational auditory model of sound localization cues in the horizontal plane. Results suggest that listeners used interaural level difference cues to localize the sound source, and that the contribution of visual and proprioceptive cues in the localization task was limited especially when the channels were reversed.