For automobiles not only will it help deaden the sound itll seal any pinhole leaks clean them out real good then mask to the sound itll seal any pinhole leaks clean them out and apply good thick layer to guard against over spray and get some.
The insides surfaces.

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,

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

#1 get ear plugs
#2 place in ears
*Voila*
Do it yourself with very little cost

For keeping leaves and stuff out the plastic gutter screens some come in sections that snap in rolls that you cut and will.

Gutters its the gutters its not the gutters its the elbow at top and bottom of leaders use that undercoating as suggested by other answer.
Gutters its not the gutters its not the elbow at top and bottom of leaders use that undercoating as suggested by other answer.
Gutters its the downspouts most likely the downspouts most likely the gutters its not the downspouts most likely the elbow at top and bottom of leaders use that undercoating as suggested by other answer.

The lower elbow where the undercoating will likely work had success spreading 14 layer of bondo onto the drips hit.