Sound: Pre-emphasize (in-place)...

A command to change the spectral slope of every selected Sound object.

The reverse of Sound: De-emphasize (in-place)....

This is the in-place version of Sound: Filter (pre-emphasis)..., i.e., it does not create a new Sound object but modifies an existing object.

Algorithm

The pre-emphasis factor α is computed as

α = exp (-2 π F Δt)

where Δt is the sampling period of the sound. Every sample xi of the sound, except x1, is then changed, going down from the last sample:

xi = xi - α xi-1

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© ppgb, November 14, 2017