demo2.dat

it is lms algo based noise cancellation program. with the p4 256 mb ram, xp/vista/dos/linux platform

There are two interesting
tests you can try:

1) You can turn ON and OFF the
control by pushing the
"Start Control" and "Stop
Control" buttons and observe
the resulting effect on the
sound cancellation.

2) Leaving the control
ON, you can slowly move the
speakers apart as shown in
sketch below. You will
observe that the sound
cancellation deteriorates as
you move the speakers. Actually,
when the speakers are about 11
inches apart the sound should be
louder than the noise alone. Keeping
the speakers about 11 inches apart, you
can again turn ON and OFF the
control and hear the sound level is
higher when the control is ON. In that
case, the two waves do not cancel each other;
on the contrary they add.

CONCLUSION: To globally cancel the
sound from a simple acoustic source,
the control source should be placed
at a distance smaller than the
wavelength (about 13 inches at
1000 Hz) divided by 12.