The Sound in Action: The link between sound perception and human behavior.

Sounds are part of our life. In principle they are just waves that reach our ears and stimulate inner receptors; nevertheless humans are able to extract relevant environmental information. Just through the sounds we can understand whether a car is approaching us, or if someone is walking or running. Since the elaboration of the information that comes from our senses is functional to plan an action for interacting within the surroundings, the aim of this thesis is to shed light on the link between sounds and the movements produced and evoked by them. By means of five experiments we investigated the relationship between action planning and sound distance evaluation; the connection between the sound produced by a movement (e.g. the footsteps' sound) and the related motor planning and finally how humans develop the ability to infer the intention of another person just by listening to the sound he/she produces. The results showed for the first time that: 1) sounds approaching the surroundings of our body (the so called peripersonal space) areperceivedandenactedin a highly specific and detailed way 2) sounds produced by movements can evoke pseudo-haptic illusions that recall the internal movement representation of that movement; 3) the absence of the sound of a movement degrades the sensory-motor integration process along with the internal movement representation; 4) the ability to re-call this internal representation depends on the level of motor experience on the heard movement; 5) from the sound of an action performed by another person, people can infer his/her intentions, but, again, this ability is experience related. In conclusion our experiments strongly sustain the fundamental role that the sound of actions play in action control and learning. We showed that from the different sound’s components as frequencies, intensity and time humans can specifically extract relevant information to guide their movements.