Chapter 10Nonlinear Processing
M. Holters and L. Köper
10.1 Fundamentals
Linear systems—filters—play an important role in audio signal processing. Linearity here means that the superposition property holds: denote the output of a system excited with input signals
and
with
and
, respectively. If the system maps the superposition of the input signals
to the corresponding superposition
at the output (for any
), it is considered linear. Systems that do not fulfill this property are accordingly called nonlinear. One important consequence of linearity, when combined with time invariance, is that systems can be fully described in the frequency domain by their transfer function. Therefore, frequency components present in the input signal can be amplified or attenuated and phase‐shifted, but ...