Dryer balls are a marketing thing much moreso than an effective product. IMO.

I tried the wool dryer balls and it was loud. Didn’t do much other than it being loud. I found to prevent static if you don't overdry there isn’t no static.

Didn't find them effective. The dog would run away with them when they fell

out of the dryer when I took out the clothes. I just let him keep them.

I tried the dryer ball thing. Bought the wool ones. Six of them. They are not hard like tennis balls and they feel solid. Very soft but solid. Once the dryer gets going, I only hear the balls if I'm listening for them and maybe standing IN the laundry room. Noise isn't a problem. Do they work? If I could only give a yes or no answer, it would be no, but, they kind do a little bit in loads of blankets or a comforter. Still not enough to warrant buying them, imo. I'll probably continue to throw them in the Dingo's blankets (a full size quilt and a sherpa throw) just to make him feel spoiled :)

They're great for practicing juggling.

We use them for down jackets....can’t use tennis balls, they are dog toys.

I have them but they are now used for decoration. They seemed to not do much if anything. They would get stuck in blankets and just roll around without helping. I don’t think they are heavy enough to do what they are intended for. And if they were heavy enough i imagine it would sound like a drum being repeatedly hit for an hour.

I put six in a large load and they work fine. Depending on load, might have a little static left. Yes you can hear them if you pay attention but not overly loud.

I bought a pack of 3 Woolzies last week, mainly to prevent clumping of small loads. Haven't done enough small loads yet to state an opinion on efficacy.

I plan to pick some up and give them a try. Worse comes to worse, I'll use them for décor too :-)