A method for estimating the orientation of a directional sound source: Application to the trawling bat N. leporinus

Modeling the behavior of bats when performing hunting tasks should take into account behavioral features such as head orientation when a call is produced. Estimating head orientation using remote acoustic recordings can be generalized to estimating the pose of any directional sound source producing a broadband signal in the ultrasonic range. Provided that microphone recordings, from known microphone positions, of the calls produced by the source are available and that source directivity is known, a mathematical method can be built up for estimating source orientation by looking for the best match between all possible source orientations and the true one using a comparison of recorded data, with values calculated from knowledge of source directivity and microphone positions with respect to source. Such a method has been tested in a laboratory environment with a Polaroid transducer as the source. Experiments show that the method estimates orientations very close to the true ones and point out the limits within which the method guarantees good performance and why. The same estimation method has been applied to calls emitted by the trawling bat N. leporinus performing hunting tasks.