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Directional Effects

Author: N.H. Crowhurst

Hearing all sounds in correct proportion is not only a matter of making sure that they come out of the loudspeaker that way. Different frequencies do not travel in rooms in quite the same way, so we may notice some peculiar effects because all the frequencies do not reach us properly.

A good loudspeaker produces a uniform sound wave but a real trumpet produces a sound like shown above. Thus the reproduced sound is not like a real trumpet.

For example, a trumpet gives out sound that is very rich in overtones. The lower (fundamental) notes of the trumpet go out in all directions, whereas the high-frequency sound is almost squirted in the direction in which the trumpet is pointed. This kind of sound production and the way in which the sound bounces around before reaching our ears have become part of our experience in listening to trumpets.

If a loudspeaker radiates all the correct frequencies to make up a trumpet sound, but distributes the high frequencies in all directions (in the same way as it does the lower frequencies), reproduction of the trumpet will not be realistic.

Last Update: 2010-11-03