Effect of interaction between movement and environment on self-generated sound perception

International audienceAuditory perception could be an interactive process with other sensory inputs and motor output. Particularly in the loudness perception although we experience in daily life that the perception of self-generated sounds is changed depending on the movement generating the sound, the mechanism of auditory processing of self-generated sound and sensorimotor interaction is still unclear. In this study, we introduced the task to generate a sound by virtually pushing an object using a haptic robot and examined whether the different stiffness of the object in the task changed the loudness perception of the self-generated sound.Fifteen healthy young adults participated in the experiment. Participants’ task was to compare the loudness of two sequential sounds (1000 Hz pure tone, 63 dB to 67dB for 1dB step). The first sound was generated by the vertical movement of the index finger. The movement was made to push an object that was produced virtually by a haptic robot. We tested two stiffness of the object and those were presented in random order. The second sound was presented without any movement. Based on the estimated psychometric function using their responses, we calculated Just Noticeable Difference (JND) and Point of Subjective Equality (PSE) in each condition and in each subject. As a result, PSE value on high stiffness condition was significantly larger than that on low stiffness condition (t(14) = 3.06, p< 0.01). JND value was not significantly different between the conditions (t(14) = 1.50, p = 0.13). The result indicated that the self-generated sound can be perceived louder when we pushed a hard object by the finger. This suggests that the interaction of the movement with the external environment is also important for the auditory processing of the self-generated sound