Help my autistic son needs dustractions

my son is 26 and lives on his own.  He cannot live with us as it is too stressful for him he needs his own space. He currently lives in a flat but he hears the neighbour upstairs and focuses on it and gets stressed as it stops him getting to sleep. I have given him earplugs to use but he finds them uncomfortable. Any advice would be greatly appreciated how he can block out noise. Apart from moving to a the middle of nowhere is there any thing that helps deal with this ?