The phrase "noise that someone hears" refers to the sounds or noise that a particular person is exposed to, either intentionally or unintentionally. This can include various types of noises such as music, voices, traffic, nature sounds, and other environmental sounds. The level of noise that someone hears can vary depending on factors like location, time of day, and personal preferences. Noise exposure is an important issue because it can have negative effects on health, well-being, and productivity if it becomes too loud or prolonged.