LSL Wiki : llCollisionSound

llCollisionSound(string impact_sound, float impact_volume)

Suppresses the default collision sounds and replaces them with impact_sound (a sound in the object's inventory or a key) played at the volume impact_volume. Supply an empty string to suppress collision sounds. Oddly, an impact_volume of 0 will disable collision particles.

Question: I'd like to play the default sound, but at a quieter volume, say 0.5. What do I use for impact_sound to still use the default sound?
Answer: That varies, depending on the material used and its sound keys.

Compare with llCollisionSprite.

A point worth making: llCollisionSound depends on the forces involved. Smaller objects need to fall from a greater height to trigger the llCollisionSound. The limit seems to be objects with a size of <0.15, 0.15, 0.15>. Smaller than that and they need to drop from more than 3m high to trigger the llCollisionSound.

One way around this is to use collision detection to trigger the sounds bearing in mind there are events for collision and land_collision.

example script

//By James Benedek
default
{
        state_entry()
        {
            llCollisionSound("", 0.0); // This will make the collision sound muted
        }
}

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Functions | Sound | Collisions