Filtering a signal is multiplication of responses and instruments themselves filter sounds.

Evidence

The effect of a filter on a spectrum is multiplicative in that the output spectrum after filtering is the product of the filter’s frequency response with the input signal’s spectrum. Thus we can easily determine the effect of a given filter on a signal’s spectrum. This is a useful technique which can be applied to the analysis of musical instruments, as we shall see later, by treating some of their characteristics as a form of filtering. In fact, filtering can be carried out using mechanical, acoustical and electrical means, and many instruments perform some form of filtering on the sounds they generate (see Chapter 4). — David Howard, Jamie Angus, coustics and Psychoacoustics, 470

Categorization

• XREF: Treating instruments as filters connects to signal-processing views of timbre; potentially useful to this reader’s target of interpreting sound through psychoacoustic concepts.