A soft piece of cloth wedged between the webbing would be the simplest cure...or invest in a waterproof hat.
I don't use the hood much, myself,so it's not something a think too much about, but it might be good little earner for someone to make a set of 4 sleeves made from a polyester fleece material to slip around the webbing (a strip of velcro to join along the edges, to hold it in place). That way the hood is not made to be too tight, but the fleece it should dampen down the snapping/popping sound.
Just a thought.
