DAFX: Digital Audio Effects, Second Edition

3.5 Conclusion

In this chapter we presented the application of modulators and demodulators in digital audio effects. We transfered concepts that are well known in communication engineering and in the design of music synthesizers into the realm of audio effects and pointed out the importance of these techniques for digital discrete-time implementations of well-known effects like ring modulation, detune effects, chorus, vibrato, flanger and rotating speaker simulation. A strong focus was put on the interaction of modulators and demodulators with filters and delays since this combination is one of the fundamental processes for many audio effects.

Using the demodulation techniques presented in this chapter, the temporal envelope of a signal can be obtained, for example. Parameters of a given audio effect to be applied to this signal may be controlled by the temporal envelope of the same, in order to arrive at a more lively and expressive sound quality. As examples, we presented the auto-wah and, more advanced, an audio morphing scheme. These applications examples may serve as a basis for experiments and further research.