Wikipedia defines Sound masking as the addition of natural or artificial sound into an environment to cover-up unwanted sound. Auditory masking may or may not consist of “white noise” or “pink noise“. Studies suggest that using sound masking in the workplace leads to higher productivity by eliminating distractions, thus allowing one to more easily focus on their tasks. At home sound masking through the use of fans and other noise production is often used as a sleep aid.
Take a look at the crying infant example to see one effective use for sound masking.