Sound of a rolling ball

Question

I'm looking for the most realistic way of playing sound of a rolling ball. Currently I'm using a Wav sample that I play over and over as long as the ball is moving - which just doesn't feel right.

I've been thinking about completely synthesizing the sound, which I know very little about (almost nothing), I'd be grateful for any tutorials/research materials/samples concerning synthesis of sound of a ball made of particular material rolling on surface made of another material. Also if this idea is completely wrong, please suggest another way of doing this.

Thanks!

Answer 1

I would guess that you'll get the biggest bang for your buck by doing a dynamic frequency adjustment on the sound that makes the playback frequency proportional to the velocity of the ball. I don't know what type of sound library you use, but most will support some variant of this.

For example, in FMOD you could use the Channel::setFrequency method. Ideally, you would compute your desired playback frequency based on your WAV's original sample frequency (Fo), the ball's current velocity (Vc), and the ball's 'ideal' velocity at which the default WAV sounds right (Vi). Something generally like:

F = Fo * ( Vc / Vi )

This will tend to break down as the ball gets farther away from the 'ideal' velocity. You might want to have several different WAVs that are appropriate for different speed ranges that you switch to at certain threshold velocities. Within each WAV's bracket, you'd do the same kind of frequency adjustment.

Another note: this is probably not something that is worth doing every frame. I'd guess that doing this more than 20 times per second would be a waste of time.

ADDENDUM: Playback frequency scaling like this can also be used for simulating the Doppler effect as well. Once you have your adjusted playback frequency, you'd perform another scale of the Frequency based on the velocity of the ball relative to the 'listener' (the camera).

Answer 2

Have you tried playing the sound forward, then playing it backward, and looping that? I use this trick graphically to creating repeating patterns. I don't know much about sound but it might work?