How do you muffle your rain gutters?

Go out and get some of that spray on undercoating used for automobiles. Not only will it help deaden the sound it'll seal any pinhole leaks. Clean them out real good then mask to guard against over spray and apply a good thick layer to the insides surfaces.

I would check out the plastic gutter screens. Some come in sections that snap in, some come in rolls that you cut and install. Any hardware and home improvement store will have them. They are made for keeping leaves and stuff out of the gutters, but will also slow down the water as it enters the gutter, and will stop rain from pinging straight into it.

You can buy plastic gutter screens now, which are suppose to keep leaves and other debris out of them, these may help reduce the noise, they are the width of the gutter and they snap in. They have lots of small holes to allow rain through but not debris.

Just a thought,

It's not the gutters, it's the downspouts. Most likely the elbow at top and bottom of leaders. Use that undercoating as suggested by other answer.

The undercoating will likely work. I had success spreading a 1/4" layer of Bondo onto the lower elbow, where the drips hit.

Ask it not to rain when you are resting, or better yet get drunk and don`t worry. If you do find an answer , can you also ask how to make the wind stop making noise as it goes thru the trees as it seems to keep me awake at night also.

#1 get ear plugs

#2 place in ears

*Voila*

Do it yourself with very little cost