Abstract: 

Bats are a paradigmatic example of « biosonar ». The bioacoustic active navigation system they use may be thought of as very similar to man-made ones, and its study presents a twofold interest: on the one hand, it may be viewed as a laboratory for understanding natural behaviors at the light of communication theory; on the other hand, it may serve as a successful guide for the development of bio-inspired systems. The observation of bat echolocation signals evidences that they consist of highly structured, ultrasonic, broadband, transient chirps, thus calling for a time-frequency description that naturally matches their nonstationary nature and allows for efficient descriptions as well as simple interpretations. It will be shown that considering biosonar signals from a time-frequency perspective easily permits to assess their performance, to discuss how close they are from optimality (with adaptation to multiple tasks such as detection, estimation, recognition, interference rejection,…), and to propose justifications for some observed robustness properties in connection with filterbank cochlear modeling. Besides biosonar issues per se, bat chirps will give an opportunity to review recent developments in data-driven time-frequency methods that are particularly well-suited to their analysis.

Biography:Patrick Flandrin graduated from ICPI Lyon (Engineer Degree in 1978) and INPG Grenoble (PhD in 1982 and "Doctorat d'État ès Sciences Physiques" in 1987). He is currently a CNRS "Research Director" at École normale supérieure de Lyon. His research interests are mostly in nonstationary signal processing (time-frequency/time-scale methods), scaling stochastic processes and complex systems. He published over 250 journal or conference papers in those areas, contributed several chapters to collective books and authored one monograph. Former Director of CNRS-GdR ISIS (2002-2005), he is President of GRETSI, the French Association for Signal and Image Processing, since 2009. Dr Flandrin has been awarded the Philip Morris Scientific Prize in Mathematics (1991), the SPIE Wavelet Pioneer Award (2001), the Prix Michel Monpetit from the French Academy of Sciences (2001) and the Silver Medal from CNRS (2010). Past Distinguished Lecturer of the IEEE Signal Processing Society (2010-2011), he is a Fellow of IEEE (2002) and of EURASIP (2009), and he has been elected member of the French Academy of sciences in 2010.
More at http://perso.ens-lyon.fr/patrick.flandrin