Noise-cancelling headphones
From ActuallyAutistic Wiki
Noise canceling headphones (and related noise reduction headphones) can be useful aids for sensory issues related to audio and noise.
They're great for use in crowded spaces and loud environments (festivals, malls, schools, concerts, etc). They are also great for sleep and focus for studying.
A variety of different kinds exist, dependent on design, decibel level, comfort level, and other factors.