Finite Element Modelling of a Loudspeaker. Part 1: Theory and Validation

The paper describes finite element modelling of an axi-symmetric loudspeaker and the resulting predicted behaviour, both the motion and the resulting sound pressure field, in both the time and frequency domains. The effect of the electrical circuit is included through post-processing. Laser and impedance measurements are shown to aid the estimation of the material parameters. Predictions are compared with measured responses and are seen to represent the main features accurately. A significant spider resonance is described. Modes can be loosely classified by the position of their dominant motion, in the spider, cone or surround. This understanding of the modal structure is used in a study of trying to reduce the influence of a cone mode by varying a surround parameter (thickness). An additional paper, Part 2 at this conference, describes applications of the model.