The sounds that are called are called with the animations. I believe they're hardcoded.
Soooo... you could make that set mute, with a single null sound, and call the sounds through a trigger that checks animal type and velocity, instead.
But there's an additional wrinkle. The engine doesn't seem to support playing sounds at a given place XYZ, so we'd have to do a workaround that would be fairly nasty. And then there's the issue of getting the Agent's velocity constantly, which could get pretty bad, since we'd have to strip the pos down to XYZ and stuff it into slots, then pull it out and compare it every half-second or so. Could get expensive.