Over the ear is nice however there are often 2 problems with them for little ones.

1. They don't fit the child and don't seal around the air and nothing.

2. The kid pulls them off all day long.

AOSafety makes some child sized over the ear that fit decently well on kids 12 months and older. Much smaller and they don't get a very good seal. A google search on "Child Ear Protection" is how I found them before.

Kids Swimming ear plugs have worked great for my son last season. They did a great job reducing the noise, fit great and he couldn't get them out. They can be found at Walgreens.