surf-lfo.ny: LFO Surf generator 
[attached to this post]

LFO: low frequency oscillator. A signal whose frequency is
generally below the human ear's ability to hear as a tone, usually
20 cycles per second [Hertz or hz].

Generates mono or stereo surf which sweeps between a lower and
upper filter frequency. Stereo surf also sweeps back-and-forth
somewhere between the left and right audio channels.

Copy surf-lfo.ny into your Audacity plug-ins folder, typically

c:\program files\audacity\plug-ins

in Windows. 

Start a new session of Audacity. To generate stereo surf, first
open a blank stereo track [alt+p, s in Audacity pre-1.3, alt+t, n,
s in 1.3 and later]. Open the generate menu. Click on 'Surf [LFO]'.

Variables with instructions:

1. Mono or stereo surf [1=mono 2=stereo]
Mono surf is heard only in the center between the two speakers, or
in the middle of your head when wearing headphones. Stereo surf
sweeps back-and-forth somewhere between the two audio channels,
depending on the next setting, Stereo Spread.

2. Stereo spread [stereo only: percent]
The larger this value, the more widely the stereo surf will move
back-and-forth between the left and right audio channels. 
When this value is above zero, the deeper section of the surf sweep
will be heard more in the left channel; below zero, the deeper
section of the surf sweep will be heard mor in the right channel.

3. Fade-in and fade-out times [seconds]
To smoothly fade in and fade out the volume at the start and end of
the surf.

4. Surf duration [minutes]
Up to sixty minutes of LFO surf.

5. Surf type [0=white noise 1=pink noise]
White noise is more of a 'hissing' sound, whereas pink noise is a
lower 'rushing' sound.
Technically, white noise is 'equal energy per frequency', whereas
pink noise is 'equal energy per octave'.

6. Surf sweep frequency [hz]
Sets how slow or fast the surf sweeps between the lower and upper
filter frequencies, and the left and right channels [for stereo
surf].


The next two variables
7. Lower filter frequency [hz]
8. Upper filter frequency [hz]
determine how low and how high the lowpass filter sweeps the surf
noise.

9. Bass frequency to boost [hz]
You can boost [increase the volume of] frequencies of the surf
sound below this setting, to get a deeper-sounding surf. Somewhat
equivalent to the bass knob on your stereo.

10. Bass boost [db]
Sets how much to boost the above bass frequency. 0db means no
boost, 6db means double the amplitude of the bass frequency, and so
on.

Note

If you get an error message 'Nyquist returned too many audio
channels', this means you tried to generate stereo surf without
first having opened a blank stereo track in audacity. See
instructions at the start of this help file for instructions on how
to do this.

Written by David R. Sky, June 17, 2007.
http://www.shellworld.net/~davidsky/nyquist.htm
Thanks to Steven Jones for pink noise generator code.
Released under terms of the GNU Public License
http://www.opensource.org/licenses/gpl-license.php 
