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While it is a true general statement that the frequency of the human voice is about 300 to 3000 Hz, this statement is generalized, over-simplified, and not entirely accurate. In fact, the human voice ranges from 20 Hz to about 14,000 Hz.
Here are some more specific facts regarding frequency range of the human voice:
The range of frequencies that young, healthy adults can hear is
between about 20 Hz to about 14,000 Hz (some up to 20,000 Hz).
These frequency numbers are in Hertz (cycles per second):
Here are some other typical frequency ranges:
Thunder - as low as 20 Hz
Hearing Frequency Ranges are also interesting to note:
Sounds which the human ear can hear range from 0 dB (so faint that only the best hearing person can hear them) up to 180 dB (as loud as a rocket taking off).
Leaves rustling - about 10 dB
A simple explanation of a waveform is that it is a graphic representation of a sound wave, which is the result of compressed air pressure propagating away from its source of compression.
A sound wave can be displayed as amplitude against time.
The loudness or amplitude of a waveform is the changing pressure from the peak of the waveform to the trough (the height of the waveform). Amplitude is measured in dB (decibel) on the vertical axis.
The distance between two successive peaks in a waveform is called the period. This measurement of time is shown on the horizontal axis.
A cycle is the amount of time it takes the waveform to go from one amplitude all the way through its amplitude changes, until it reaches the same amplitude again. (The times a sound wave crosses zero vertically.) This range consists of 360 degrees.
The frequency of the waveform is how many cycles it goes through each second, where one Hz (hertz) is one cycle per second.
Pitch refers to the basic frequency at which a sound vibrates, also known as its fundamental frequency, or F0 ("eff-zero"). This also refers to how high or low the sound is perceived. Pitch is often used synonymously with frequency; the higher the pitch, the higher the frequency.
Fundamental frequency (F0) is the lowest frequency of the sine waves composing a complex sine wave. The two higher frequency components are the second and third harmonics, the fundamental frequency is also called first harmonic.
ELF - Extremely Low Frequencies:
FREQUENCY is a measure of the rate at which electromagnetic waves are
generated. Frequency is measured in cycles per second, called hertz (Hz) after
the German scientist who first discovered radio waves. (1 Hz equals one cycle
per second.) The field around power lines, for example, is predominantly 60 Hz.
Radio wave frequencies range from 300 Hz to billions of hertz. Electromagnetic
waves with similar frequencies can be grouped together. These groupings form the
ELECTROMAGNETIC SPECTRUM, with low-frequency waves (sometimes called ELF for
"extremely low frequencies") at one end and high-frequency waves at the other.
Radio waves, microwaves and infrared light can be found at the lower end of the
spectrum. Ultraviolet light, X-rays and gamma rays occupy the upper end. Visible
light, including sunlight, occupies the middle region. Microwaves are used in
the transmission of telephone and telegraph messages, in communications between
earth and orbiting satellites, and in relaying certain television broadcast
ELF/VLF radio waves penetrate deeply beneath the surface of the earth and interact with the geologic structure of the earth. This interaction induces secondary fields with measurable effect at and above the surface of the earth. Proper understanding of the physics of the generation and propagation of ELF/VLF waves and their interactions with earth materials will allow these waves to be used for applications such as sub-surface communications and exploration of the subsurface geological structure.
Electromagnetic radiation with a high frequency carrier wave (e.g., radiowave) and an extremely low frequency (ELF) modulation is considered amplitude modulated (e.g. TDMA mobile phone systems). The modulation can also be pulsed where the carrier wave is switched on and off very rapidly in the rate of about 100 pulses per second (e.g., GSM mobile phone systems), while continuous wave (cw) radiation is generated essentially at a single frequency (e.g., analog mobile phone systems).
Natural ELF/VLF Radio - also called "Natural Radio" - are audio-frequency radio signals of Earth in the approximately 200 Hz to beyond 10,000 Hz (10 kHz) spectrum which are not man-made but occur naturally in nature. Most of the best phenomena are heard between 400 Hz and 5 kHz. Interest in naturally-occurring ELF/VLF radio phenomena such as "whistlers" and "chorus" has enjoyed a rapid resurgence during the past 10 years on the part of academic research via orbiting space-probes and ground-based monitoring efforts, and also notably amongst amateur hobbyists world-wide thanks to easy availability of sensitive receiving equipment.
You can listen to some of the Natural ELF Radio sounds with streaming audio (Real Audio) courtesy of NASA.
Sferics - Mainly the ubiquitous snap, crackle and pop of lightning all over the earth, this can be heard anytime, anywhere, on frequencies from 1 Hz to beyond 100 MHz. Just tune your AM radio to an empty frequency. Sferics below deserve special mention.
The ELF frequency range is critically important to the Navy because of its
value in providing a way to communicate with submerged submarines. As a result
of the high electrical conductivity of sea water, signals attenuate (or
decrease) rapidly as they propagate downward through it. In effect, the sea
water "hides" the submarine from detection while simultaneously preventing it
from communicating with the outside world through normal radio transmissions. We
record wideband ELF/VLF (~200 Hz to 20 kHz) data at Palmer Station, Antarctica.
Extremely Low Frequency (ELF, 30-3000 Hz) and Very Low Frequency (VLF, 3-30 kHz)
are frequency bands to denote where the signals we measure are in the
electromagnetic spectrum. Our signals happen to be in the audio range, so that
if they were sound waves, you could hear them.
The degree to which a signal is attenuated depends on its frequency, however.
The lower the frequency, the more deeply a signal can be received in sea water.
In order to receive conventional radio transmissions a submarine must travel at
slow speeds and be near the surface of the water. Both of these situations make
a submarine more susceptible to enemy detection.
HAARP is a project funded by the US Senate and operated by the US Navy & Air Force. HAARP or "High Frequency Active Auroral Research Program", was supposedly started to communicate with submarines deep in the ocean using ELF radio waves which can penetrate the ocean as well as the earths surface. With what the power HAARP has it can focus all its radio waves into a single beam in the sky, which effectively exceeds its 3.6 Million watt power status. Still to get a better idea, its 72,000 times more powerful than the U.S.'s most powerful radio station. With this much power the possibilities for use are endless, of course activists ,conspiracists, and environmentalists all have their own ideas for applications of this weapon / utility, both good and bad.
"Natural Radio" describes naturally-occurring electromagnetic (radio) signals emanating from lightning storms, aurora (The Northern and Southern Lights), and most importantly, the Earth's magnetic-field (the Magnetosphere). This is a presentation of Earth's natural radio emissions that occur in the extremely-low-frequency to very-low-frequency (ELF-VLF) radio spectrum--specifically, at AUDIO frequencies between approximately 100 to 10,000 cycles-per second (0.1 - 10 kHz). Unlike sound waves which are vibrations of air molecules that our ears are sensitive to, natural radio waves are vibrations of electric and magnetic energy (electromagnetic waves) which--though occurring at the same frequencies as sound--cannot be listened to without an audio-frequency ELF-VLF radio receiver to convert the natural radio signals directly into the same sound frequencies. Another amazing realm of nature is thus ready to be explored and observed.
Also TRULY fascinating:
If you could see my mind, if you really look deep,
then maybe you'll find...
That somewhere there will be a place, hidden behind my
Locked in the room in the corner you see,
a voice is waiting for me, to set it free.
I got the key, I got the key.
I locked it inside my imagination, but I'm the one who's got the combination.
Some people didn't like what the voice did say,
So I took the voice and I locked it away.
I got the key, I got the key
Don't look back, look straight ahead, don't turn away, then the voice it said
Don't look back, yesterday's gone, don't turn away, you can take it on