``Reverberation'' is an interesting sound effect which can be generated easily with the 56002. A simple reverb is an echo, generated by adding a delayed output signal to the input signal:
where is a constant (say, 0.5), and is large enough to produce delays of, say, 50 ms to 500 ms.
An echo generated using Equation 1 has a disadvantage in that the frequency response is not flat - i.e., some frequencies will be enhanced over others. This can be fixed using an equation of the form
This gives for all .
Another interesting effect is a ``chorus'' effect, which would be generated by several instruments playing the same notes at about the same times, but with small changes in amplitude and timing. A simple chorus effect can be generated with the equation:
where and are different. (For a true chorus effect, these would change slightly with time.) To keep the system from saturating, all the 's must be less than 1/3.