String Interface

Referring to Fig.4.18 showing a basic string simulator, it is possible to eliminate the explicit comb-filtering corresponding to the hammer striking position. The uniform spacing of the force pulses in the excitation signal is the same as the delay needed for the striking-position comb filter. As a result, the physical force-injection signal can be replaced by the comb-filtered version , where is the travel time from the striking point to the agraffe and back. The comb filtering can be applied to the excitation table prior to the shaping filter(s), or the shaping filter(s) can be designed to convert the excitation table directly into rather than . In either case, the final excitation signal simply drives a single filtered delay loop, as shown in Fig.5.11.

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written by Julius Orion Smith III
Julius Smith's background is in electrical engineering (BS Rice 1975, PhD Stanford 1983). He is presently Professor of Music and Associate Professor (by courtesy) of Electrical Engineering at Stanford's Center for Computer Research in Music and Acoustics (CCRMA), teaching courses and pursuing research related to signal processing applied to music and audio systems. See http://ccrma.stanford.edu/~jos/ for details.