Auditory and vocal communication in animals

In our description of behaviorally relevant features of environmental sounds and vocalizations, we have relied extensively on the statistical analysis of natural sounds.  In this line of research, we use a comparative approach to refine this statistical analysis and to more directly assess the validity of our statistical analysis with behavioral experiments.
 For our studies with songbirds and in human speech, we performed statistical analyses of zebra finch song, Bengalese song and human speech spoken by adult American speakers.   In collaboration with Y. Cohen (U Penn), we did an initial study of the acoustical structure of macaque vocalizations.  In an approach similar to the one that is performed our laboratory, Cohen and his collaborators used that information to relate this acoustical structure to the response properties of auditory neurons in the ventral prefrontal cortex of the macaque, an area which has been implicated in semantic processing of communication sounds both in humans and in macaques (Cohen et al, J Neurophys 2007). 

In collaboration with S. Glickman (UCB, psychology) and N. Mathevon (Univ. St. Etienne, France), we are also studied the rich repertoire of the spotted hyena.   We recorded a large set of vocalizations produced in different contexts: groans and growls produced in non antagonistic approach behavior, loud whoops produced during separation and displacements and the giggle sounds produced when the animals are frustrated.   We found that the acoustical structure of the groan changed when the animals where approaching an inanimate (bone) versus an animate object (cub) and we found that the structure of the hyena giggle bouts carried information not only about the identity of the sender but also about its social rank (Mathevon et al., BMC Ecology, 2010).

We also performed playback experiments in both songbirds and hyenas.  In these experiments, we are systematically manipulating the communication calls and testing behavioral responses in various playback and operant conditioning experiments.  Our statistical analyses of the sounds, our neurophysiological data in songbirds and our psychophysical data in humans suggest that birds will be particularly sensitive to certain degradations in song in recognition, discrimination and preference tasks.