van der Schaar, M., Gallego, P., André, M. A standard method for sperm whale coda classification 19th Conference of the European Cetacean Society, La Rochelle, France, Apr 2005 Abstract: Sperm whales (Physeter macrocephalus) produce a limited variety of broadband acoustic signals whose combinations include usual, rapid and slow clicks, creaks and codas. The use and importance of these signals are still poorly understood, but codas are believed to play an important role in the communication process of socializing sperm whales. They consist of a short series of clicks repeatedseveral times and are mostly heard when the whales are gathering at the surface. It has also been hypothesis ed that codas could be specific to a group and geographical location. To confirm these assumptions and compare codas from different data sets it is necessary to agree on and use a common standard for the classification process. An objective method for the classification of normalized sperm whale codas is proposed. The k-means algorithm is used for analysing the data; its clusters are accepted when they resemble a normal distribution in the direction of their principal components. Probabilistic outcome of the kmeans algorithm is avoided by initialisation of the cluster centres. In addition a naming standard is suggested which accurately describes the rhythm of a coda. Project: Creation of the Laboratory of Applied Bioacoustics (LAB). Development of underwater acoustic technology to assess noise pollution in the ocean Project: Noise pollution effects on cetaceans