I first started using sponge rubber earplugs like these some years ago when I had noisy neighbours, it was the only way I could get a good night's sleep..

All the chemist's/pharmacists sell them so noise must be a problem for more people than we think.
I still keep a box around the house for when noisy delivery lorries or workmen are in the street, and I also pop them in when doing a spot of DIY hammering and drilling or hoovering.
They come in several different shapes and are far better than cotton wool, they're not just ordinary foam rubber, they've got special sound-deadening properties.
I like the brown ones on the left best, you have to roll one end between the fingers then insert them but remember to leave enough sticking out so you can grip it to remove it later.
PS- I developed tinnitus 25 years ago when living next door to a yapping dog (before i discovered earplugs) and my ears have been ringing ever since; it's annoying but i've managed to get used to it-