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Noise Pollution
- Started on 11-01-03
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- Noise Pollution Last update:
2004-04-04
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- Send email to nonoise@plex.us
with "Noise Info" in the subject line if you have info to
contribute. Thanks for all your input.
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- Basic principles and histroy of sound.
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- Basic
Principles :
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- The Sound and Light Spectrum
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- Video is a combination of light and sound, both of which are
made up of vibrations or frequencies. We are surrounded by various
forms of vibrations: visible, tangible, audible, and many other
kinds that our senses are unable to perceive. We are in the midst
of a wide spectrum which extends from zero to many millions of
vibrations per second. The unit we use to measure vibrations per
second is Hertz (Hz).
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- Sound vibrations occur in the lower regions of the spectrum,
whereas light vibrations can be found in the higher frequency
areas. The sound spectrum ranges from 20 to 20,000 Hertz (Hz).
Light vibrations range from 370 trillion (1 trillion =
1,000,000,000,000) to 750 trillion Hz. When referring to light, we
speak of wavelengths rather than vibrations.
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- As a result of the very high frequencies and the speed at
which light travels (300,000 km per second), the wavelength is
extremely short, less than one thousandth of a millimeter. The
higher the vibration, the shorter the wavelength.
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- Not all light beams have the same wavelength. The spectrum of
visible light ranges from wavelength of 0,00078 mm or 780 nm
(nanometer) to a wavelength of 0,00038 mm (380 nm). We perceive
the various wavelengths as different colors. The longest
wavelength (which corresponds to the lowest frequency) is seen by
us as the color red followed by the known colors of the rainbow:
orange, yellow, green, blue, indigo, and violet which is the
shortest wavelength (and highest frequency). White is not a color
but the combination of the other colors. Wavelengths which we are
unable to perceive (occurring just below the red and just above
the violet area), are the infrared and ultraviolet rays,
respectively. Nowadays, infrared is used for such applications as
remote control devices.
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- Visible light as part of the electromagnetic spectrum.
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- Note: visible light is only visible because we can see the
source and the objects being illuminated. The light beam itself
cannot be seen. The beams of headlights in the mist for instance,
can only be seen because the small water drops making up the mist
reflect the light.
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- More references:
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- Characteristics
of Sound and Color
- Color
wavelength
- SkepticTank
- The Sound of Color
- Light
Waves
- A
Hotlist on Sound, Light & Waves
- How do
we sense light?
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- Google
Search: "color spectrum" "sound" - 6,770 links
- Google
Search: "color spectrum" "sound" "wavelengths" - 404
links
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- Middle section is under development as of 04-04-04
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- The effect of sonar or noise on dolphins.
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- MK
34 Gun Weapon System (GWS)
- New
evidence of Navy's active sonar damage to whales and dolphins -
DIVERNET News for Divers
- Groups
Sue To Stop Navy LFAS Sonar Harming Whales, Dolphins
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- Development of sonic weapons.
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- Fortean
Times - Sonic Weapons :
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- Sound is a waveform, with low infrasonic frequencies having a
long wave length (measured in tens of metres), and with high
ultrasonic frequencies having a short wave length (measured in
millimetres). The frequencies associated with ultrasound are most
familiar from their utilisation by the medical profession, chiefly
for diagnostic imaging.
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- While the ears are designed to detect a limited range of
frequencies &endash; the human auditory range is between 20Hz and
20,000Hz (1Hz = 1 cycle per second) &endash; different frequencies
can affect the whole body and, at volume, can be felt in almost
any part of the body. Even with industrial ear protectors, sound
waves are able to enter the head via the nose and mouth which are,
in turn, linked to the ears by the structure of the skull. Sounds
that are higher in frequency than 20,000Hz &endash; ultrasound
&endash; are inaudible to humans, while sounds lower than 20Hz
&endash; infrasound &endash; are inaudible but can, on occasion,
be felt resonating within the body itself. Exposure of unprotected
ears to infrasound can also cause an increase in pressure within
the middle ear, disturbing the sense of balance.
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- The natural world is awash with infrasound created by thunder,
earthquakes, tsunamis, volcanoes, shifting tectonic plates and
even winds. The ability of animals, such as bats and dogs, to hear
ultrasound is well documented, but numerous animal species can
also hear &endash; and utilise &endash; infrasound. Elephants,
have a hearing range that is believed to start from 0.1Hz,
enabling them to hear the distant rumble of thunderstorms far
earlier than humans can and to communicate over long distances.
Other animals may even employ infrasound as a weapon: recent
research suggests that tigers are able to deliver a
physically-stunning 18Hz roar immediately before attacking.
Similarly, sperm whales seem to use pulses of infrasound to stun
the large squid that form the basis of their diet.
[...]
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- According to the Working Paper on Infrasound Weapons produced
by Hungary for the United Nations in 1978 4, the frequency that is
thought to be most dangerous to humans is between 7 and 8Hz. This
is the resonant frequency of flesh and, theoretically, it can
rupture internal organs if loud enough. Seven hertz is also the
average frequency of the brain's alpha rhythms; thus this
frequency has been described as dangerous but also relaxing.
Whether exposure to such infrasound can trigger epileptic
seizures, as some fear, remains unclear; experimental data on
exposure to such frequencies gives a variety of results. It should
be noted, however, that the strobe light effect associated with
triggering epileptic seizures flashes at an equivalent rhythm.
Frequencies below 50Hz commonly lose their coherence and are
perceived to pulse or fluctuate, which is analogous to the
strobing beat of a modulated light.
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- It was NASA scientists in the early 1960s who produced most of
the documentation of the effects of infrasound on the human body;
they were particularly keen to discover how proximity to the low
frequencies produced by rocket engines would affect their
astronauts, especially during launching. Their extensive tests
confirmed that, at certain volumes, infrasound did indeed have
various physiological consequences. According to results published
by NASA researcher GH Mohr, frequencies between 0Hz and 100Hz, at
up to 150-155dB, produced vibrations of the chest wall, changes in
respiratory rhythm, gagging sensations, headaches, coughing,
visual distortion, and post-exposure fatigue. 5 Subsequent
research has determined that the frequency that causes vibration
of the eyeballs &endash; and therefore distortion of vision
&endash; is around 19Hz. [...]
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- Delta (0.5 &endash; 4Hz), Theta (4Hz &endash; 7Hz), Alpha (7Hz
&endash; 12Hz), and Beta (13Hz &endash; 30Hz).
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- ABCNEWS.com
: Sonic Bullets to Be Acoustic Weapon of the Future :
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- Anyone who has seen Tom Cruise fire his state-of-the-art sound
wave gun at his pursuers in Minority Report no doubt assumes it is
a weapon from the arsenal of science fiction. But such a weapon,
or at least a less-glamorous version, is scientific fact.
[...]
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- "[For] most people," said Norris, "even if they plug
their ears, it will produce the equivalent of an instant migraine.
Some people, it will knock them on their knees."
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- The device emits so-called "sonic bullets" along a narrow,
intense beam up to 145 decibels, 50 times the human threshold of
pain. It usually doesn't take that much to stop someone, as we
learned in a demonstration in the company parking lot. The
acoustic "weapon," in the demonstration model, looks like a huge
stereo speaker, except this one sports urban camouflage.
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- The operator chooses one of many annoying sounds in the
computer &emdash; in this case, the high pitched wail of a baby,
played backwards &emdash; and aims it at us. At 110 decibels, we
were forced to walk out of the beam's path, our ears ringing. Had
we stayed longer, Norris said our skulls would literally start to
vibrate.
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- CNN.com
- Troops get high-tech noisemaker - Mar. 3, 2004 :
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- Gruenler compares the LRAD's shrill tone to that of smoke
detectors, only much louder. It can be as loud as about 150
decibels; smoke detectors are in the 80 to 90 decibel range.
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- "Inside 100 yards, you definitely don't want to be there,"
said Gruenler, adding that the device is recommended for a range
of 300 yards or less.
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- Hearing experts say sound that loud and of that high a
frequency -- about 2,100 to 3,100 hertz -- could be dangerous if
someone were exposed to it long enough.
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- "That's a sensitive region for developing hearing loss," said
Richard Salvi, director of the Center for Hearing and Deafness at
the University at Buffalo. "The longer the duration, the more
serious it is."
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- Gruenler concedes that permanent hearing damage is possible if
someone were exposed to the sound for lengthy periods.
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- But he said the high-pitched tone is intended to only be used
for a few seconds at a time.
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- More references:
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- Google
Search: "sonic weapon" - 2,217 links
- Google
Search: "sonic weapons" - 917 links
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