A command to filter every selected Sound object. The resulting Sound object has a lower spectral slope.
The reverse of Sound: Filter (pre-emphasis).... For an example, see Source-filter synthesis.
The de-emphasis factor α is computed as
|α = exp (-2 π F Δt)|
where Δt is the sampling period of the sound. The new sound y is then computed recursively as:
|y1 = x1|
|yi = xi + α yi-1|
© ppgb, March 9, 2003