Hi,
I wrote the other day asking about Noise Gates and got some really
good replies which greatly helped in my understanding of how they
work. Thanks Guys!!!

Today, I'm asking about a High Pass Filter. Again, I just started
working on a project where the computer captures samples of someone's
speech. Each of these samples is run through a 50 Hz High Pass Filter
to improve the quality of the sample. I've done a lot of reading
about High Pass filters and think I understand pretty well how they
work. What I don't understand though is a couple of the variables in
the program where the filter is actually implemented. I'm hoping
someone out there knows java and can help tell me what they mean.
Code follows and then my questions...

public class HighPass50
{
static int NZEROS = 5;
static int NPOLES = 5;
static double GAIN = 1.095980088e+00;

double xv[] = new double[NZEROS+1];
double yv[] = new double[NPOLES+1];

public HighPass50() {}

public void process(short data[])
{
for (int i=0; i data.length; ++i)
{
xv[0] = xv[1];
xv[1] = xv[2];
xv[2] = data[i] / GAIN;
yv[0] = yv[1];
yv[1] = yv[2];
yv[2] = (xv[0] + xv[2]) - 2 * xv[1] + ( -0.9479259375 *
yv[0]) + ( 1.9469976496 * yv[1]);
data[i] = (short)yv[2];
}
}
}


Looking at the method above, I don't understand the meaning of the
'GAIN' variable (and more specifically the number it is set to). Is
this likely the cutoff frequency? Also, in the next to the last line
of the method, where yv[2] = ..., there are two numbers in this line
that I have no idea what they mean. The number "-0.9479259375" and
the number "1.9469976496". My guess is that the number
"-0.9479259375" is the lowest frequency possible (zero Hz) and that
"1.9469976496" is the highest frequency possible. This would make
sense if the GAIN variable was the cutoff frequency. Again, that is
my best guess! Can someone help with my understanding???

Thanks in advance,

Scott