White noise machine
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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, which has a harsh sound, but pink noise, whose power rolls off at higher frequencies, or other colors of noise.
Use
White noise devices are available from numerous manufacturers in many forms, for a variety of different uses, including audio testing, sound masking,
Manufacturers of
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
Audio jammers
White noise machines are used to diminish the potential for recording or overhearing conversations. Republican Glen Casada had a white noise machine installed in his office to prevent against eavesdropping.[5]
Smart speaker blockers have been developed. For example, Bracelet of Silence is a bracelet that outputs white noise to protect privacy against digital recording from smart speakers.[6] 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).[7]
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,[8] 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).[9]
See also
- Pink noise
- White noise
- Colors of noise
- Sound masking
- Tinnitus masker
- Sound Princess
References
- ^ 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.
- ^ Adams, Cecil (1997-09-12). "Will sleeping in a closed room with an electric fan cause death?". The Straight Dope. Chicago Reader, Inc. Archived from the original on 2012-05-10. Retrieved 2007-08-02.
- ^ Watanabe, Toshifumi, and Masahiko Morita. (1998-08-31). "Asphyxia due to oxygen deficiency by gaseous substances." Forensic Science International, Volume 96, Issue 1, Pages 47–59. Retrieved on 2007-09-06.
- ^ Gill, James R., Susan F. Ely, and Zhongxue Hua. (2002). "Environmental Gas Displacement: Three Accidental Deaths in the Workplace." Archived 2007-09-30 at the Wayback Machine The American Journal of Forensic Medicine and Pathology, 23(1):26 –30, 2002. Retrieved on 2007-09-06.
- ^ Ebert, Joel. "White noise machines installed in Glen Casada's office; ex-aide eavesdropped on meeting rooms". The Tennessean.
- ^ Hill, Kashmir (14 February 2020). "Activate This 'Bracelet of Silence,' and Alexa Can't Eavesdrop". The New York Times.
- ^ Wixey, Matt (August 2019). "Sound Effects – Exploring acoustic cyber-weapons" (PDF). media.defcon.org. pp. 1–81. Retrieved 15 March 2023.
- ISSN 0362-4331. Retrieved 2021-05-20.
- S2CID 16155364.