Please explain: What is a particle diagram. I know what ear muffs are.
You could do it something like this although I must describe some of it.
First I would draw a wavy line from left to right to stand for sound waves. Paerhaps a sinusoidal wave.
/\/\/\/\/\ the tops and bottoms are rounded. And I would make these rather large to indicate a LOUD sound.
Then I would draw a couple of straight lines with a space between and put dots to represent filler material between the lines.
|........| you can label the particles between as sound absorbing material but they can be scattered better than I can do it on th computer. You may want to label the lines I have drawn as "outside of ear defender."
The I would draw on the RIGHT side of the ear defender another sinusoidal wave with much less intensity. That is, make the waves lower so there is less distance between the top of the crest and bottom of the trough. (The waves on the left might be made quite large to illustrate loud sounds and the waves on the right would show reduced sound levels). You can probably think of some other things to make this look good but this should get you started. I tried to find a drawing on the web but no luck.
Ear defenders are like ear muffs they are made of muffins which can help with helping you to stop you getting tooth in your ear drum (Fun Fact--- I did not just make that all up there really are teeth in your ear drums!)