主题：Optimal Position of a Loudspeaker in a Rectangular Room

Optimal Position of a Loudspeaker in a Rectangular Room

Final student paper of Fabrice Ducomble, electronics engineer

Introduction

The position of a loudspeaker in a room, rectangular or not, influences in a sensitive way the quality of a sound to such a point that you can get better results with a bad loudspeaker judiciously placed than with a good speaker placed without planning. In fact, the imperfection appearing in the loudspeaker response curve can be attenuated by the resonance created in the room or, on the contrary, be amplified by them. It should be noted that the position of the listener is almost as important as the source of the sound.

The problem then is to find the optimum
positions for both the source and the listener.

We are particularly interested in the behavior of the low frequencies in the room with the presence of the loudspeaker. It is, in fact, in this range of frequencies that the interaction between these two components is the most noticed. So, a study in depth modal behavior has been carried out, from their formation to their influence on the distribution of the sound field.

From this study we devised a model that permitted us to predict the behavior of low frequencies in a rectangular room. This model takes into account another very important phenomenon : The influence of the distance from the walls on the power of the emitted sound.

The program carried out is based on this model. It calculates the response curves relative to all possible positions regarding the source-listener, and chooses, with the help of two tests, the best among them. The optimum position of the loudspeaker, and of the listener, is then the positions corresponding to the best response curve.

This research can be divided into three parts :
1. The study of the influence on the proximity of the walls on the sound power emitted.
2. The study of modal behavior and the establishment of a model permitting the determination of the influence on the sound field.
3. The presention of the results.