[chuck-users] question about input detector from adc (MIC)

[=?BIG5?Q?=BCB=AB=D8=A7=D3?=]

Dear all,
I would like to detect "sound" input from MIC (adc).
It means that if any sound occure, one event or anything should be done.
My thought is that:
 
adc => gain g => blackhole;
1 => g.gain;
g.last() => float x;
while( true ) {
if ( std.fabs(x) == 1. )
<<<x>>>;
}
 
But the x is always 0.
So  how to do it??
Thanks a lot!!
Lewis