Musican's earplugs might be a better option. I have a set of Hearprotek with interchangeable variable dB reduction inserts.
@UKBloke I'm just a bit nervous that musician earplugs won't block out enough sound, but I will have a look. Children's voices are one of the things that my ears are sensitive to.
@aura would you wear earmuffs as well? I don't mind looking daft, but would like to be able to take part in the day, hear people talk etc.