Tutorials and Topics - Peabody Computer Music

Tutorial 26Frequency domain signalprocessing using pfft~You can use this information to create signal processing routines based onamplitude/phase data. A spectral noise gate would look something like this:A spectral noise gateBy comparing the amplitude output of cartopol~ with the threshold signal sent into inlet 2of the pfft~, each bin is either passed or zeroed by the *~ objects. This way only frequencybins that exceed a certain amplitude are retained in the resynthesis (For information onamplitude values inside a spectral subpatch, see the Technical note above.).Convolution and cross-synthesis effects commonly use amplitude and phase data fortheir processing. One of the most basic cross-synthesis effects we could make would usethe amplitude spectrum of one sound with the phase spectrum of another. Since thephase spectrum is related to information about the sound’s frequency content, this kindof cross synthesis can give us the harmonic content of one sound being “played” by thespectral envelope of another sound. Naturally, the success of this type of effect dependsheavily on the choice of the two sounds used.212