Audacity Support Forum / Audacity and Nyquist / Nyquist Reference Manual / Nyquist Examples and Tutorials
Sound examples: wind.ogg - multiwind.ogg
This page describes a "wind" effect created by Alex. The basic function is as follows:
(defun wind (&optional (dur 3) (scal 3) (cps 590) (bw 40))
(stretch dur
(mult (env 0.07 0.08 0.1 1 0.6 0.8 1)
(sum
(reson (scale scal (noise)) cps bw 2)
(reson (scale (mult scal 1.13) (noise))
(mult cps (pwl 0 0.74 0.2 0.96 0.5 0.8 0.75 1.16 0.9 0.97 1 0.74 1))
(mult bw 1.042)
2)))))
- Sound example: wind.ogg
The basic idea is to use bandpassed noise to create the sound of wind. In this example, two bandpass filters are added together. The first uses a fixed center frequency and bandwidth, and the second uses a piece-wise linear function to control the center frequency. The entire sound is multiplied by an envelope and stretched to the desired duration. Note how several optional parameters can be used to change the default behavior.
A slight elaboration of the wind function uses several copies of wind in sequence with slight overlap:
(defun multiwind ()
(simrep (i 4) (at (* i 2.9) (wind))))
- Sound example: multiwind.ogg
One problem with this approach is that the wind sound becomes periodic. This could be solved by using noise or random numbers to generate the center frequency variation rather than a fixed envelope.
Audacity Support Forum / Audacity and Nyquist / Nyquist Reference Manual / Nyquist Examples and Tutorials