A deprecated command that creates a FormantFilter object from every selected Sound object by band filtering in the frequency domain with a bank of filters whose bandwidths depend on the pitch of the signal.

The analysis proceeds in two steps:

1. We perform a pitch analysis (see Sound: To Pitch... for details).

2. We perform a filter bank analysis on a linear frequency scale. The bandwidth of the filters depends on the measured pitch (see Sound & Pitch: To Spectrogram... for details).