Is there a way to change expression values per keyframe?

I suppose you could create frequency and decay arrays, with entries for each keyframe and modify the expression to something like this:

freqArray = [3,2,1,4];

decayArray = [5,6,7,6];

n = 0;

if (numKeys > 0){

  n = nearestKey(time).index;

  if (key(n).time > time) n--;

}

if (n > 0){

  freq = freqArray[Math.min(n-1,freqArray.length-1)];

  decay = decayArray[Math.min(n-1,decayArray.length-1)];

  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

Dan