![Digital-clock-radio-premium](https://upload.wikimedia.org/wikipedia/commons/6/65/Digital-clock-radio-premium.jpg)
A white noise machine is a device that produces a noise that calms the listener, which in many cases sounds like a rushing waterfall or wind blowing through trees, and other serene or nature-like sounds. Often such devices do not produce actual
white noise
In signal processing, white noise is a random signal having equal intensity at different frequencies, giving it a constant power spectral density. The term is used, with this or similar meanings, in many scientific and technical disciplines ...
, which has a harsh sound, but
pink noise
Pink noise or noise is a signal or process with a frequency spectrum such that the power spectral density (power per frequency interval) is inversely proportional to the frequency of the signal. In pink noise, each octave interval (halving ...
, whose power rolls off at higher frequencies, or other
colors of noise
In audio engineering, electronics, physics, and many other fields, the color of noise or noise spectrum refers to the power spectrum of a noise signal (a signal produced by a stochastic process). Different colors of noise have significantly ...
.
Use
White noise devices are available from numerous manufacturers in many forms, for a variety of different uses, including audio testing, sound masking,
sleep
Sleep is a sedentary state of mind and body. It is characterized by altered consciousness, relatively inhibited sensory activity, reduced muscle activity and reduced interactions with surroundings. It is distinguished from wakefulness by a de ...
-aid, and
power-napping. Sleep-aid and nap machine products may also produce other soothing sounds, such as music, rain, wind, highway traffic and ocean waves mixed with—or modulated by—white noise. Electric fans are a common alternative, although some Asian communities historically avoided using fans due to the
superstition that a fan could
suffocate them while sleeping.
[Surridge, Grant. (2004-09-22)]
"Newspapers fan belief in urban myth."
''JoongAng Daily'', via joongangdaily.joins.com and archive.org. Retrieved on 2007-08-30.[Gill, James R., Susan F. Ely, and Zhongxue Hua. (2002)]
"Environmental Gas Displacement: Three Accidental Deaths in the Workplace."
''The American Journal of Forensic Medicine and Pathology'', 23(1):26 –30, 2002. Retrieved on 2007-09-06. White noise generators are often used by people with
tinnitus
Tinnitus is the perception of sound when no corresponding external sound is present. Nearly everyone experiences a faint "normal tinnitus" in a completely quiet room; but it is of concern only if it is bothersome, interferes with normal hearin ...
to mask their
symptoms. The sounds generated by digital machines are not always truly random. Rather, they are short prerecorded audio-tracks which continuously repeat at the end of the track.
Manufacturers of
sound-masking devices recommend that the volume of white noise machines be initially set at a comfortable level, even if it does not provide the desired level of privacy. As the ear becomes accustomed to the new sound and learns to tune it out, the volume can be gradually increased to increase privacy. Manufacturers of
sleeping aids and
power-napping devices recommend that the volume level be set slightly louder than ''normal music listening level'', but always in a comfortable listening range.
Sound and noise have their own measurement and color coding techniques, which allows specialized users to identify noise and sound according to their respective needs and utilization. These specialized needs are dependent on certain professions and needs, e.g. a
psychiatrist who needs certain sounds for therapies and treatments on a mental level, and patients who have conditions such as insomnia, anxiety, and, tinnitus (these conditions are managed with special devices which are designed to create certain sounds that treat such conditions at a mental level). A white noise machine has “white” as the color code given to that noise having a particular
frequency spectrum
The power spectrum S_(f) of a time series x(t) describes the distribution of power into frequency components composing that signal. According to Fourier analysis, any physical signal can be decomposed into a number of discrete frequencies, ...
.
Audio jammers
White noise machines are used to diminish the potential for recording or overhearing conversations.
Republican
Republican can refer to:
Political ideology
* An advocate of a republic, a type of government that is not a monarchy or dictatorship, and is usually associated with the rule of law.
** Republicanism, the ideology in support of republics or agains ...
Glen Casada
Richard Glen Casada Jr. (born August 2, 1959) is an American politician, member of the Republican Party in the Tennessee House of Representatives, where he represents District 63 ( Williamson County). He was the Speaker of the Tennessee House of ...
had a white noise machine installed in his office to prevent against eavesdropping.
Smart speaker blockers have been developed. For example,
Bracelet of Silence is a
bracelet
A bracelet is an article of jewellery that is worn around the wrist. Bracelets may serve different uses, such as being worn as an ornament. When worn as ornaments, bracelets may have a supportive function to hold other items of decoration, suc ...
that outputs
white noise
In signal processing, white noise is a random signal having equal intensity at different frequencies, giving it a constant power spectral density. The term is used, with this or similar meanings, in many scientific and technical disciplines ...
to protect privacy against
digital recording
In digital recording, an audio or video signal is converted into a stream of discrete numbers representing the changes over time in air pressure for audio, or chroma and luminance values for video. This number stream is saved to a storag ...
from
smart speaker
A smart speaker is a type of loudspeaker and voice command device with an integrated virtual assistant that offers interactive actions and hands-free activation with the help of one "hot word" (or several "hot words"). Some smart speakers can a ...
s. Bracelet of Silence is portable and not attached to smart speakers, thus it is possible that this device can be used to prevent eavesdropping of other devices as well, for example smartphones and laptops.
There is not a lot of research on the impact of loud sounds at inaudible frequencies (and their respective audible artifacts and harmonics).
Design
Most modern white noise generators are electronic, usually generating the sound in real-time with audio test equipment, or via electronic playback of a digital audio recording. Simple mechanical machines consist of a very basic setup, involving an enclosed fan and, optionally, a speed switch. This fan drives air through small slots in the machine's casing, producing the desired sound. The first fan-based white noise machine was the Marpac Dohm, which was invented in 1962 and is frequently credited as the original domestic use white noise machine.
Risk
One paper found that of the 14 white noise machines tested at maximum volume, all exceeded maximum safe sound levels for infants (50 dB). Three exceeded safe levels for adults (85 dB).
See also
*
Pink noise
Pink noise or noise is a signal or process with a frequency spectrum such that the power spectral density (power per frequency interval) is inversely proportional to the frequency of the signal. In pink noise, each octave interval (halving ...
*
White noise
In signal processing, white noise is a random signal having equal intensity at different frequencies, giving it a constant power spectral density. The term is used, with this or similar meanings, in many scientific and technical disciplines ...
*
Colors of noise
In audio engineering, electronics, physics, and many other fields, the color of noise or noise spectrum refers to the power spectrum of a noise signal (a signal produced by a stochastic process). Different colors of noise have significantly ...
*
Sound masking
Sound masking is the inclusion of generated sound (commonly, though inaccurately, referred to as "white noise" or "pink noise") into an environment to mask unwanted sound. It relies on auditory masking. Sound masking is not a form of active noise ...
*
Tinnitus masker
Tinnitus is the perception of sound when no corresponding external sound is present. Nearly everyone experiences a faint "normal tinnitus" in a completely quiet room; but it is of concern only if it is bothersome, interferes with normal hearin ...
*
Sound Princess
References
{{reflist
Noise (electronics)
Privacy
Sleep
Hardware device blockers