// patch
Impulse i => ResonZ filter => dac;
// set filter Q
5 => filter.Q;
// set filter gain
5 => filter.gain;

// go
while( true )
{
    // fire!
    1 => i.next;
    // modulate the filter frequency
    50 + (1 + Math.sin( now/second*3 )) * 500 => filter.freq;
    // advance time
    20::ms => now;
}