I'm looking for more information on RE Analysis. I like the Kyma tool, but I'm having trouble predicting the results (especially in regards to reducing the severe distortion, which does not seem to be related to the amplitude of the wave).
-- SimonAmarasingham - 26 Feb 2004
RE Analysis is a form of spectral analysis where you are looking for the spectral envelope rather than a highly detailed partial-by-partial analysis. (Analogous to the difference between the amplitude envelope of a signal and the sample-by-sample waveform of the signal.) The higher the order of the RE analysis, the more peaks there can be in the resulting spectral envelope.
The most interesting results seem to come from sounds produced by sources that have strong, dynamic formants, for example, human speech/singing, tablas. Sounds with relatively fixed formants (e.g. musical instrument tones) are not as interesting (since their spectral envelopes tend to be static). You can do a form of cross-synthesis by obtaining the spectral envelope of one sound and feeding a different sound through the resultant RE filter.
My current favorite settings for the RE Analysis are:
Order: 16
Updates: 100
Averaging: 0.015 s
Also I recommend feeding the original sample through a HighPassFilter? with a cutoff around 80 hz prior to doing the RE Analysis. (Use Action>Record to disk to create a new sample with the HPF applied.) This helps reduce any DC offset and slightly reduces the dominance of the fundantal frequency's amplitude. It helps the RE capture the the formant structure or spectral envelope (the part of the sound which, for the most part, is invariant with respect to the fundamental frequency changes).
The resulting RE filter is extremely sensitive to input amplitude--much more so than you might imagine, To get an idea of what kinds of inputs will work well with this filter, listen to the EX file that it produces: very bright, broad-band, and extremely soft. That's why Noise with an amplitude <= 0.01 can work well as an input to these filters.
For addtional RE tips and variations, please see the "yellowbox" on page 200 of Kyma X Revealed!
-- CarlaScaletti - 26 Feb 2004