White noise generators have a variety of uses, including reducing stress, improving sleep quality, enhancing concentration, calming infants and providing conversational privacy in the workplace. The increasing popularity of these machines is a testament to their utility, and a growing number of manufacturers offer a wide variety of sound machines for a multitude of uses. When compared to the alternatives, a white noise generator provides a safe, economical and natural remedy for a variety of conditions.
Healthy human ears can generally detect sounds within a frequency between 20 to 20,000 Hz (hertz, or cycles per second). White noise consists of sound at all frequencies within this range at an equal volume (and therefore indistinguishable individually).
Human hearing does not hear all audible frequencies with equal efficiency -- it favors sounds within the range common to human speech (200 to 8,000 Hz). Sounds having a frequency below and above this range have to be louder to be heard by human ears. Therefore, white noise is heard as a mid-range hiss, similar to the sound of a waterfall or fan. The lowest and highest frequencies generally can't be heard.
Humans have been evolutionarily designed to constantly monitor their environment for potential threats. Against a backdrop of repetitious sounds, an unexpected noise instinctively elevates our alert status, and our attention automatically orients toward the source. This process occurs whether we are awake or asleep. How alarmed or alert we become depends on how loud the unexpected noise is compared to background noise levels, as well as, to some extent, the nature of the noise.
White noise is able to mask potentially alarming sounds by reducing the difference in volume between background noise and an unexpected noise. In other words, a white noise generator can buffer human hearing against alarming or distracting noises by increasing background noise levels. This protects us from the stress of continual awareness, allowing us to sleep more deeply or relax more fully, which in turn reduces our stress levels and makes us healthier.