From Wikipedia, the free encyclopedia
Acoustic Noise Cancellation Development
The idea of personal noise protection by actively
controlled headphones was originally documented in a 1960 Russian patent
application. In the United States, the idea for active noise cancellation for
helicopter and aircraft pilots was patented by Dr. Lawrence
J. Fogel as early as the mid 1950s U.S.
Patent 2,866,848,
U.S.
Patent 2,920,138,
U.S.
Patent 2,966,549
and Canadian patent 631,136. According to Bose, the company started noise cancellation
involvement after Dr. Amar Bose went on a 1978 flight to
One source notes that nearly simultaneously, the US company Bose and Sennheiser
in Germany presented active headsets for aircraft pilots, citing a 1986 American Society of Mechanical
Engineers paper about the Bose product and a 1988 Funkschau (see de:Funkschau)
paper about the Sennheiser. Boses first noise cancelling headsets were released
to the public in 1989.
After about 10 years of research and development Bose released their first
consumer level noise reducing headphones for pilots called the Aviation
Headset, released in 1989. The current revision provides active equalization
as well as active noise reduction.
Like all such technology, it mixes an inverted sample of the ambient sound
outside the headset with the sound that reaches the inside of the headset,
partially cancelling out the noise. Active (battery-powered) noise cancellation
is never perfect, and is better at low frequencies than at high frequencies.
As with all active noise cancellation technologies, it requires a source of
power a small battery inside the headset to perform the cancellation.
