890 Chapter 30
allows fast checking of the performance of such circuits as low- or high-pass fi lters or
tone controls.
30.4 Distortion Measurement ........................................................................................
One of the more important characteristics of any audio system is the extent to which
the signal waveform is distorted during its passage through the system. Where the input
signal (fi n) is of a single frequency, and this distortion is due to some nonlinearity in the
transfer characteristics of the signal handling stages, this nonlinearity will generate a
series of further spurious signals occurring at frequencies that are multiples of the input
frequency (or frequencies).