Background noise is a constant nuisance and causes major difficulty when it comes to processing information and sorting the important from the unimportant.
It is for this reason that noise reducing headphones or earmuffs can come in very handy in loud spaces. Headphones can lower the overall decibel rate of background noise while still allowing your child to hear someone speaking to them.
Some Autistic people listen to music discreetly with their noise cancelling headphones as a more discreet coping mechanism to their Sensory sensitivities.