Modal synthesis is a technique that can be used to efficiently simulate the sounds of objects that exhibit a relatively small number of exponentially decaying sinusoids, such as impulsively struck bars, plates, or blocks.
These exponentially decaying sinusoids correspond to vibrating modes of the objects in question.
In the traditional modal synthesis approach, each of these modes is modeled with a second-order digital filter of the form
where the fk are the mode frequencies in Hz, the rk are the pole radii controlling the decay rates, and Ts is the sample period.
These resonant filters are typically connected in parallel, tuned and calibrated from measured recordings, and then excited with an appropriate ``dry hit'' (and/or residual) signal, as illustrated in Fig. 12.
A traditional modal synthesis block diagram.