EVP Frequency Ranges

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Measuring terms:
1,000,000 cycles per second = Megahertz (MHz)
1,000 cycles per second = Kilohertz (KHz)
1 cycle per second = Hertz (Hz)

Some ghost investigators say that a recorded voice in the ELF range is quantifiably EVP because the human voice cannot go below 250 or 300 Hz.

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:

Most energy concentrated below 1000 Hz.
Vowels have most of their energy below 1000 Hz.
Consonants have most of their energy above 1000 Hz.
Harmonics in voice can go above 3500 Hz.

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).
We perceive speech mainly in the frequency range of 500 Hz to 3000 Hz.

The frequencies which have the most significance for speech lie between about 100 Hz and 4,000 Hz.

Human voice ranges from 20 Hz to about 14,000 Hz (typically about 300 to 4000 Hz).

The fundamental frequency (F0) for an adult male voice is around 120 Hz (80-200 Hz).
A speaker with a bass voice will produce sounds with a F0 of between 75 and 150 Hz.
The typical F0 range for an adult female voice is around 220 Hz (140-500 Hz).
A speaker with a soprano voice will produce sounds with a F0 of 400+ Hz.

These frequency numbers are in Hertz (cycles per second):

1                 Approx. beginning of brain waves
6.66           Theta brain waves
7.85           Alpha brain waves
15.7           Beta brain waves
30-30.56   Government VLF stations
32-33        Government VLF stations
34-42        Government VLF stations
50              Approx. Upper limit of brain wave frequencies
60              Produces an audible sound

Here are some other typical frequency ranges:

Thunder - as low as 20 Hz
Piano - 25 Hz to 4,100 Hz
Bass drums - as low as 30 Hz
Bass guitar - 30 Hz to 200 Hz
Bass Tuba - 44-349 Hz
Cello - 66-987 Hz
Guitar - 83-880 Hz
Trombone - 83-493 Hz
French Horn - 110-880 Hz
Trumpet - 165-987 Hz
Clarinet - 165-1567 Hz
Violin - 196-3,136 Hz
Flute - 262-3,349 Hz
Cymbals - up to 15,000 Hz
Squeal of Bats - about 20,000 Hz


Hearing Frequency Ranges are also interesting to note:

Dog Hearing Frequency Range - about 50-45,000 Hz
Cat Hearing Frequency Range - about 45-85,000 Hz
Bat Hearing Frequency Range - about 2,000-120,000 Hz
Porpoise Hearing Frequency Range - about 75-150,000 Hz



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).

Typically, we speak between 45-60 dB loud.

Here are a few more decibel scales:

Leaves rustling - about 10 dB
Stream Flowing - about 15 dB
Whisper - about 20-50 dB
Ticking Watch - 20-30 dB
Bass Drum - 35-115 dB
Organ (orchestral) - 35-110 dB
Quiet Street - 40 dB
Cymbal - 40-110 dB
Violin - 42-95 dB
Quiet Conversation - 45-60 dB
Trumpet - 55-95 dB
Busy Office - 60 dB
Home hi-fi system - about 60-90 dB
Piano - 60-100 dB
Loud Conversation - 70 dB
Normal City Traffic - 70 dB
High-speed electric train - 70-100 dB
Vacuum Cleaner - 75 dB
Hair Dryer - 80 dB
Cafeteria - 80 dB
Slamming Door - 80 dB
Motorcycle - 90 dB
Lawn Mower - 90 dB
Garbage Truck - 100 dB
Screaming Baby - 115 dB
Thunder - 120 dB
Construction Site - 120 dB
Race Car - 120-130 dB
Rock Band - 120-130 dB
Pain Threshold - 130 dB
Jet Taking Off - 140 dB
Rifle Shot - 160 dB
Rocket launch - 200 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:

A great deal of attention is paid by the scientific and experimenter communities to the frequencies below 9 kHz. Here you can monitor, and actually hear a wide range of "natural radio" phenomena. Events such as "whistlers", which are believed to be the sound of the energy pulse of a lightning bolt following the earth's magnetic field, can be heard with special radio receivers. These radios (which are surprisingly easy to build) are capable of tuning down to 300 cycles and below, where these signals are heard. There are many other sounds from known and unknown sources that are being investigated as well. Many who assist the scientific community in such studies do not even listen to the sounds produced, but monitor such things as the changes to background noise using pen traces on paper tape or computer sampling of variations in measured voltages. Through this activity further knowledge is being developed about the radio propagation in this region, which still contains many mysteries.

From http://web.archive.org/web/20010907195739/http://www.provcomm.net/pages/joe/introlf.htm

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 signals.

From http://www.elecenergy.com/understanding.htm


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.

From http://web.archive.org/web/20010907195739/http://www.fas.org/irp/program/collect/haarp.htm

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).

From http://web.archive.org/web/20010907195739/http://www.electric-words.com/cell/industry/canadian/radio.html

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.

From http://web.archive.org/web/20010907195739/http://www.triax.com/vlfradio/natradio.htm

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.

Listen to sample http://web.archive.org/web/20010907195739/http://www.altair.org/hear/krakl.wav
More at http://web.archive.org/web/20010907195739/http://www.altair.org/natradio.htm


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.
From http://web.archive.org/web/20010907195739/http://www-star.stanford.edu/~scr/Research.html

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.
More about the Navy's ELF system:



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.

From http://web.archive.org/web/20010907195739/http://www.txdirect.net/~area51/haarp/documents/haarpintro.html


"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.

From http://web.archive.org/web/20010907195739/http://image.gsfc.nasa.gov/poetry/sounds/sounds.html


Also TRULY fascinating:

There is evidence that ELF magnetic waves can affect brain waves. These set of experiments were designed to study the effects of ELF rotating magnetic fields on the brain.

The specific ELF frequencies I was interested in studying are 6-10 Hertz. These frequencies are the same as those produced by the human brain in the theta and alpha states. Generally, specific brain wave frequency ranges can be associated with mood or thought patterns. Frequencies below 8 Hertz are considered theta waves. While these seem to be some of the least understood frequencies, they also seem to be associated with creative, insightful thought. When an artist or scientist has the "aha" experience, there's a good chance he or she is in theta. Alpha frequencies are from 8 to 12 Hertz and are commonly associated with relaxed, meditative states. Most people are in an alpha state during the short time immediately before they fall asleep. Alpha waves are strongest during that twilight state when we're half asleep and half awake. Beta frequencies (above 12 Hertz) coincide with our most "awake" analytical thinking. If you are solving a math problem, you're brain is working at beta frequencies. Most of our waking hours as adults are spent in the beta state.

A question of importance is: "If we can electronically shift the brain wave frequencies to alpha or theta, will a person's moods or thought patterns change to those commonly associated with those frequencies?". In other words, if we can electronically move a person's brain waves to the alpha frequencies, will they become more relaxed? Will their state of consciousness change to coincide with their brain waves, even if those brain waves were electronically induced? These are important questions with far reaching implications.

From http://web.archive.org/web/20010907195739/http://www.borderlands.com/archives/arch/elf.htm


horizontal rule



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 comedian face.

You will find somewhere there's a house, and inside that house there's a room.

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.

Voices, I hear voices

In my head the voice is waiting, waiting for me to set it free.

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

Voices, I hear voices, voices, I hear voices


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



-Russ Ballard