Dear colleagues, I am pleased to announce the publication of the following paper in the Journal of the Acoustical Society of America: Koblitz, J.C., M. Wahlberg, P. Stilz, P.T. Madsen, K. Beedholm, and H.-U. Schnitzler (2012). Asymmetry and dynamics of a narrow sonar beam in an echolocating harborporpoise. Journal of the Acoustical Society of America. 131 (3), 2315-2324 URL:http://link.aip.org/link/?JAS/131/2315 DOI: 10.1121/1.3683254 Abstract: A key component in the operation of a biosonar system is the radiation of sound energy from the sound producing head structures of toothed whales and microbats. The current view involves a fixed transmission aperture by which the beam width can only change via changes in the frequency of radiated clicks. To test that for a porpoise, echolocation clicks were recorded with high angular resolution using a 16 hydrophone array. The beam is narrower than previously reported (DI = 24 dB) and slightly dorso-ventrally compressed (horizontal -3 dB beam width: 13°, vertical -3 dB beam width: 11°). The narrow beam indicates that all smaller toothed whales investigated so far have surprisingly similar beam widths across taxa and habitats. Obtaining high directionality may thus be at least in part an evolutionary factor that led to high centroid frequencies in a group of smaller toothed whales emitting narrow band high frequency clicks. Despite the production of stereotyped narrow band high frequency clicks, changes in the directionality by a few degrees were observed, showing that porpoises can obtain changes in sound radiation. Please feel free to contact me for a pdf copy. With kind regards, Jens Koblitz Jens.Koblitz@uni-tuebingen.de Biosonar Lab Animal Physiology Insitue for Neurobiology University of Tuebingen Auf der Morgenstelle 28 D-72076 Tuebingen Germany