User Guide

156
Module: Master effects
So, reverb and delay would seem to be two birds of
the same feather. Not so: even if a delay effect is able
to generate regularly repeating echoes, it lacks an
essential quality of reverb:
Though reverb also consists of echoes, there is a
distinction between early and late reflections. Early
reflections arrive shortly after the direct sound. In
physical terms, these are clearly defined, highly
focused waves. Because they have not been diffused
by multiple reflections, they provide a more direct
and accurate impression of the sound source and
shape and size of the room in relation to the position
of the listener.
Late reflections arrive much later and in far greater
numbers. These late reflections are almost random,
so they do not leave you with much of an impression
of the physical properties of the room. This is why
they are also called diffuse reflections (diffusion
parameter). Diffuse reflections - or the lack thereof -
are crucial in determining the acoustics of a room. A
good concert hall, for example, absorbs these
reflections so well that they decay exponentially.
Another important property of reverb is the
incoherence of sound waves when they arrive at our
ears. Do not let the terminology baffle you, the
explanation is actually quite simple. Our ears are
accustomed to hearing sounds first in one ear and
then with a slight delay in the other in closed
venues. That gives us the impression of space:
Picture a concert hall with a very high ceiling. The
acoustic waves first reflect off the walls. Because you
are not standing equidistant from each wall, the
sound waves arrive at your right ear earlier or later
than at the left ear. If the venue’s ceiling was very
low, the sound waves would be reflected off it first
and both your ears would hear them simultaneously.
Neuron.book Seite 156 Montag, 23. Dezember 2002 2:28 14