I'm going to take a guess at this, see if it makes sense to you? Remember in jh school you'd have your sneakers on and chirp to class thinking you were some car spinning the tires shifting gears anshit?
You have this belt that is being dug into one side of the belt's UUVVUUUUVVU teeth. Not all U's wear evenly, right? Same goes with the chain rung. Sprocket wise to chain wise, this chain comes around and it has hi/low spots, right?
You can hear someone come along with a bad or dry drive chain by the waaa-waaa-waaa sound, right? So is not the same hi/low spots happening too with belt? So on lift, the belt rides up the other side. Drive side is quiet. Coast side is loud. Same noise like inside the pumpkin of the rear end of a car. Say the pinion bearing is loose? On coast, it makes the contact points stick out away from the drive footprint. So on coast, the footprint goes something like this... Take a wine glass, lick the tip of your finger, now run your finger around the glass so it begins to vibrate and sing some pitch of ringing noise. Notice how the farther out the foot print to the edge of the glass, you now have this harmonic noise of a new, out to the edge footprint.
So as the drive side of the belt wears, there is a gap on the coast side, you lift, the belt rides up the tooth, it sings or chirps as if coasting with a bad ring and pinion set in the pumpkin; to the chain riding up a worn sprocket; is the wider tooth U on the one side; is to spit the U down the middle and you have a deeper wear pocket on the drive side than the coast side. Make sense go look at a worn chain sprocket.
You rub both hands together and you ask yourself which side did not wear a pattern? And now the gap of you pushing the bottom of the belt up, you see how the drive is [set to go tension] wise? The bottom belt is riding under the coast side? So on lift/coast, the bottom rung is tight, the top rung of the belt is loose.
We on the same page yet?
