If you must work in an excessively noisy environment, you should wear protectors. You should also wear them when you are using power tools, noisy yard equipment, or firearms. For them to work properly they should be of the appropriate shape, and correctly inserted. They may cause irritation especially if dirty. They are usually disposable and will not fit properly if repeatedly re-used.
Ear muffs fit over and around the outer ear, as shown in the accompanying image.
They too need to be appropriately fitted with correct headband tension, and avoiding glasses or hair which will impair the seal and hence the protection. The use of combined ear plugs and muffs is controversial. As with all personal protection - this is the last line in the protection hierarchy. Hearing protection not worn as constantly and consistently as it should be.