
A command to filter every selected Sound object. The resulting Sound object has a lower spectral slope.
The reverse of Sound: Filter (preemphasis).... For an example, see Sourcefilter synthesis.
The deemphasis 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:
y_{1} = x_{1} 
y_{i} = x_{i} + α y_{i1} 
© ppgb, March 9, 2003