Reflection of sound

When a sound wave hits a surface it is reflected, absorbed or spread or even a
combination of this.

The strength of an individual reflection is determined by the acoustic properties in
the surface, from which it is reflected, as well as the distance it has covered.

When a sound wave hits a completely even surface it is reflected as a mirror image. All irregularities in the reflecting surface will influence the reflection.

If a reflecting surface has absorbing properties some of the energy will be absorbed
but the pattern of reverberation will also be affected by the angle the sound wave
comes from. This especially applies to reverberations from a thin board which
begins to vibrate because of a sound wave so that the reverberation angle fluctuates.

Surfaces which are not even spread the energy of the sound wave. A diffuse surface can be regular for e.g. curved or irregular, for e.g. like diffuse surfaces which are used in studios. From a design point of view it is important to remember that all diffusion from surfaces is to a certain extent dependant on frequency. This means that the size of the inconsistencies must be in a certain ratio to the wave length of the sound wave. This also results in the surface, which spreads in one frequency scale, to create focused or very strong reflective reverberations
in another frequency scale.