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Terrestial Acoustic Spectra

  1. Oct 3, 2004 #1
    I'm looking for data on "acoustic noise" produced regularly by the earth, nothing man-made. In particular I'm looking for noise sources outside of the normal range of human hearing (20Hz-20kHz). Of course there are numerous terrestial noise sources, such as earthquake tremors, but those aren't predictably regular.

    To be even more specific, what I'm really looking for are noise source candidates for terrestially emitted "acoustic zeitgebers". For those whoe aren't familiar with the term zeitgeber, it means time-giver. It's commonly used in the field of study of biological rhythms. A good example of a non-acoustic terrestial zeitgeber is the daily sunrise/sunset transition that sets the body's circadian phase.

    So, in summary a candidate for a terrestial acoustic zeitgeber would have to be a "noise" source produced regularly by the earth in a cyclical fashion (though not necessarily daily). Again, if such a zeitgeber exists it's probably outside the range of normal human hearing or I'd most likely already know about it.

    Thanks in advance to any who can help!
  2. jcsd
  3. Nov 5, 2004 #2

    How about 13.6 day swing to peak gravitational pull by the moon?

    Or the often quoted, but least understood, figure for the earth's frequency of 7.8hz?

    Since you allow for other than hearing range, then how about the smell of fresh soil, rain on rocks, etc. These should be in the olfactory ranges of 3-12hz, and 29-103hz.

    those kind??

  4. Nov 6, 2004 #3

    Thanks and yes, these are exactly the kinds of things I'm looking for.
    See below=>

    Very interesting possibility. I assumed the moon's gravity cycle would correpsond to the 28.5 day lunar period. Why is it only 13.6 days? As a percentage, what deviation from "norm" does it induce in the earths gravitational field over the cycle? Can you direct me to a reference on this?

    Another good candidate. Where does the 7.8Hz frequency come from? Is it constant or does it have some cyclicity to it? Again, a reference or any elaboration would be great.

    Most fascinating. I had no idea olfactory senses had an acoustic basis. Could you elaborate on this please??

    Much thanks!
  5. Nov 7, 2004 #4
    further info

    1. lunar cycle - a lunar month is 27.32 days, which is the distance between full moons, which describes a pattern of light . This effect is secondary to that of gravity, which is distance between the 2 masses. This pattern is 13.66 (1/2 of lights') because the "new moon" (dark) is at the same proximity to the Earth as during the "full moon" (light). It is this cycle that produces the greatest high/low tide variation.

    13.__ and 27.__ are sacred to some. They represent the most harmony possible in a circle/orbit/cycle. It is in part due to modern man's ignorance of this that we have to consistently correct "our time" to reflect nature.

    The effect (your "gravitational field") is that today is always .00000002 seconds longer than tomorrow. The moon moves away from earth a few centimeters each year.


  6. Nov 7, 2004 #5


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    Staff: Mentor

    T.Roc is referring to neural oscillatory activity observed in olfactory nervous systems and has nothing to do with acoustics.
  7. Nov 7, 2004 #6
    2. The "7.8"hz. When I said "least understood", that includes me too! After 15 years in studying these type of things, I have found no formula to produce it. However, the frequency, and consistency of references to it incline me to leave it on the table until then.

    It is said to be shared by the Earth, and us humans. Also related - it is the beginning of the "bridge" alpha frequencies into the theta (EEG brainwaves). This is where attention moves from conscious to subconscious in meditation.

    #3 to follow...

  8. Nov 7, 2004 #7


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    Staff: Mentor

    27.32 days is the time it takes for the moon to complete one orbit around the earth, it is called the Sidereal month, it does not match the monthly lunar phase cycle you described.

    A lunar cycle of 29.53 days (actually varies between 29.2 and 29.9 days) is the Synodic month and is the time it takes for the moon to complete the cycle from new moon to new moon.
  9. Nov 7, 2004 #8

    3.)) First a quick reply to Evo. The correction is correct (not "acoustical"), while I was without need, this is a public forum, and others might need the reminder.
    Besides being prompted by Reality_Patrol that this was the type of information sought, the original question left doors open to "non acoustical" data. Putting "acoustic noise" in quotes alerts the reader to a potentially broader definition than is common, "the field of study of biological rhythms" is non acoustical, as is a "non acoustic terrestial zeitgeber".

    3. A "time-giver" is like a marker of an event in "time" without the use of time. Just patterned distance that informs you of where in the cycle that you are.

    One of the best biological "stamps" is the nose. From birth, we accumulate our own collection of smells. Once smelled, always remembered. It is our environment/culture that dictates the range, and the "good/bad" response. These are the "gamma range" olfactory frequencies 29-103hz. Nature allows for more than just a "book of smells" though. There is a theta olfactory range as well (3-12hz). This is shared by the alpha and theta ranges of the brain (again the "bridge"). This allows for "anchors" or zietgebers to be formed in high energy situations. If you are mauled (but survive) by a bear, the strong (close proximity) odor of a bear will then always induce emotions similar to the original event. On the other hand, pleasant odors present when you first meet the one you love will resonate with that emotion. These are not normal "memories", they are fully chemically induced "states". I believe that the energy needed for our nervous system to manifest this comes from these simultaneous and harmonic frequencies being received by the brain.

    In the field of study of Vibrations, the math involved is the same for all types of waves, oscillations, and dualistic charges.

    I have no idea of what it is you are really trying to understand, but enjoyed your thread.

  10. Nov 8, 2004 #9
    How about the http://www.campusprogram.com/reference/en/wikipedia/c/ch/chandler_wobble.html [Broken] would it qualify with it's 435 days period?
    Last edited by a moderator: May 1, 2017
  11. Nov 8, 2004 #10
    I'm studying biological rhythms. You seem to have studied brain rhythms for some time. While I'm not excluding brain rhythms from my study, I'm not actively looking at them. I'm focused on physiological rhythms - a most overlooked subject and one that's responsible for many health problems. What I'm trying to find are presently unknown zeitgebers. One example should make this clear: the female menstrual cycle probably evolved to phase lock to the synodic lunar cycle. Why doesn't it? Most likely the natural zeitgeber is blocked somehow by the modern environment. Many have hypothesized gravity is the zeitgeber, but your answers proves that's not the case (the periods are too different). My second speculation would be that the lunar zeitgeber is most likely the lunar X-ray shower produced on and near the full moon from the solar wind. It would penetrate clouds and natural coverings (as would be a requirement) but modern building practices probably provide too much shielding to allow it to be detected by the body. Thanks for your answers and your time.

    Thanks for your answers as well. One last question, can you provide a link to a good description of the moons orbit/trajectory around the earth?

    No, I don't think so. I don't know of any bio-rhythm that has a 465 day cycle. Then again maybe there is one but it's just not widely known. Thanks for the suggestion though - good to keep in the 'ol back pocket.
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