freq = 3;
decay = 5;
n=0;
if (numKeys > 0){
n = nearestKey(time).index;
if (key(n). time > time) n--;
}
if (n > 0) {
t =time - key(n). time;
amp = velocityAtTime(key(n). time - .001);
w = freq*Math. PI*2;
value + amp* (Math.sin (t*w)/Math.exp (decay*t)/w);
} else
value
