Script required for llCollisionSound() to work?

I'm building an irregular cave-type floor and want to use llCollisionSound() to get rid of all the unpleasant bumping noises as I walk around.

I had hoped that I could call llCollisionSound() to turn off the noises and then have the script delete itself. Seemed to me that collision sound should be a property of the prim.

But that doesn't seem to be the case. It seems like the script has to be running in order for it to have an effect.

Has it always been this way? It seems stupid for me to keep scripts running in all of these prims just to get rid of the collision sound! Shouldn't I be able to set it and forget it?

Anyway, here's what I wanted to do:

silence()
{
    llCollisionSound( "", 0.0 );
}

die()
{
    llRemoveInventory( llGetScriptName() );
}

silenceAndDie()
{
    silence();
    die();
}

default
{
    state_entry()
    {
        silenceAndDie();
    }

    on_rez(integer start_param) {
        silenceAndDie();
    }
    
}

A script that's running but not doing anything (that is, it's only waiting on an event that isn't going to happen) shouldn't use significant resources.