For children with Figure-ground processing problems, noises prevent them from understanding much of what is said.
The tower operators had to listen to simultaneous voice transmissions over the same radio band, and make decisions about who was saying what.
Some children (and adults too) have particular difficulty in discriminating speech or other sounds in the presence of back ground noises--even small ones. For them noises are more than minor annoyances. They are a major cause of learning disabilities.
These individuals are constantly switching their attention to unimportant sounds such as foot scraping, light buzzing, whispering, pencils falling, blowing wind and fans etc. etc. etc.
Hence, they miss most of what they need know, and find listening unrewarding, if not fatiguing.
Conversely, it is possible to improve this perceptual ability with practice.