Investigations about the directivity of sound sources

The book - a doctoral dissertation - deals with theoretical aspects of the radiation of sound sources. These are carefully studied and applied to the modelling of real sound sources. Based on the physical description of sound sources using classical acoustic wave theory, two parametrical models of sound source radiation are developed. The first one, the spherical harmonics model, gives a complete description of a sound field in spherical co-ordinates using spherical harmonics and Hankel functions. Methods for determining the model parameters are studied in detail. The second model uses monopole synthesis to describe the directivity of sound sources. The parameters of this model are found by minimizing the squared error between the measured and the modeled directivity. Both theoretical models are applied to measured data of the directivity of loudspeakers and of a human speaker. Results of a psychoacoustic validation of the models in the context of a binaural room simulation system are given and discussed in detail. One of the main potential applications of the directivity models is the compression of measured 3-dimensional directivity data of sound sources, e. g., in the context of auditory-virtual-reality generators.