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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 | 
© Paul Boersma 2003-03-09