The Heterodyne Hypothesis

[Guest spurfoot]

In the forum "Member sightings", bipedalist, in post #20 mentions the following :

If it helps any I have experienced the "fluttering" in the ear effect when near or in the home range of what I suspect were Sasquatch. Usually, for me it is then associated with other bass vibratory sounds (and no I don't have a neurological/vascular/hearing/seizure disorder, lol) and occasionally a sound such as someone running their wet finger around the rim of a wine glass. The only noises besides stick breaking that accompanied creatures the evening of my sighting was a fluttering like a moth sound at close distance when there were no moths evident and the bass vibratory sounds/feelings/pressure waves which seemed to be more syncopated and rhythmic rather than steady/constant.

My interpretation of that observation is that the so called infrasound sometimes mentioned associated with BF might not really be infrasound, but, is instead the heterodyning of two closely spaced ultrasonic pitches. Thus "syncopated and rhythmic rather than steady/constant" . This possibility makes a lot of sense when you consider how hard it is to have an efficient infrasonic emitter. The sasquatch is known to be able to emit very high pitched sounds. Emitting two of them close together in pitch and very intense at ultrasound frequencies would be a highly efficient way to create the illusion of infrasound in the ear of the hearer provided that the ear of the hearer is non-linear when ultrasonic intensity is high.

This seems to be the first time this interpretation has been proposed, so, robust discussion is in order. Comments from bipedalist are especially solicited.

[bipedalist]

Well I'm not an audio engineer, but I am an astute listener and observer of behavior. There is much that is going on with the Sasquatch phenomenon that is for sure. Capacity for piercing whistles, associated animal mimicry and metallic almost ringing sounds in the same "phrase" or outburst so to speak. Roars, loud yells with descending and ascending components; whoops; samurai vocals, etc. It is certainly a puzzling phenomenon..... but there is also a body of evidence suggesting that clicking sounds are also integrated into sound vocabulary as well. In that respect....it could also be an incidence of a cetacean-type sound process involved which would of course be in that ultrasonic zone. The bass vibratory aura has occurred in several instances and confirmed in multiple situations and geographical locales. It sounds as if the recording apparatus for both infrasound and prob. ultrasound are both very expensive. I can't disagree with the possibility of ultrasonic involvement in putative Sasquatch utterances. So I think the heterodyne hypothesis has much merit.

[HOLDMYBEER]

........ The sasquatch is known to be able to emit very high pitched sounds.

Interesting thought... but can you cite any documentation of this fact?

[Guest]

:

The sasquatch is known to be able to emit very high pitched sounds.

Correction: bigfoot enthusiasts and researchers are able to detect very high-pitched sounds they attribute to bigfoot. Noone has definitively connected them doing so visually.

http://www.skepdic.com/infrasound.html

This site was interesting about infrasound.

The suggestion that infrasound is produced by animals as large as tigers suggests that bigfoot could certainly make such sounds. I think this is more likely than heterodyning high-pitches which would more proabably be produced from smaller creatures.

[Guest]

Interestingly, I have experienced similar ear flutterings in the woods during my youth. I have not experienced these in may years, and as a youth experienced a certain reticence to go alone into the woods where I lived. Often had the feeling of being watched or needing to flee. The more I think back, the more I wonder if my isolated wee bit hill and glen was not stalked by BF creatures. Not familiar with heterodyne principle. Does the principle apply to the blending of any two vibratory tones to create a new tone?

In response to newest post: aha, gotcha. It has been implied that BF, due to its size and possible air sacs could produce low pitched infrasounds. Perhaps BF could use high pitches as well, or a combo thereof...

I find this topic interesting as a player of the great highland bagpipe. It has been theorized (though not tested, that I know of) that the combination of high and low pitched sounds coming from the pipes has some infrasonic/ultrasonic, (even just sonic?) affect on other animals (people, horses). Meldrum mentioned it in LMS. May pertain to what you are talking about. What BF is purportedly cable of seems mostly out of human range of hearing. Perhaps not completely?

Edited February 11, 2012 by notgiganto

[Guest spurfoot]

The account by bipedalist contains mention of a high pitched sound "occasionally a sound such as someone running their wet finger around the rim of a wine glass " .

In general, "screams like a woman", and such are notoriously high pitched, also testify to high pitched emissions.

Antfoot, you are correct that there is no absolute proof of the association, nonethless, the temporal and spacial correlations are high enough to be presumptive. Given the large size of BF, direct emissions of infrasound is a possibility, and, heretofore has been the default assumption. However, the physics of sound emission argues against efficient emission of infrasound. Efficient emission seems necessary given the large effect the fluttering or infrasound has upon people.

I thank everyone for their comments. What is needed is an experimental record of the phenomenon. Given the rarity of meeting a BF, few people are likely to have suitable equipment with them. Bipedalist, given what I know about his situation, is one of the few people for whom it might pay to construct and carry suitable recording apparatus.

I hope to later publish on this thread a block diagram of a suitable recording apparatus.

[Guest Thepattywagon]

In music, a tone resulting from the playing of two other notes simultaneously is called a 'difference tone'. If I recall correctly, the third note's pitch will be at a frequency equal to the difference of the first two notes. The "buzzing" in the ear from a difference tone is something I've experienced often, particularly when playing music with flute players.

I'm not sure what effect the combining of an extremely high pitch and a subsonic frequency would have as far as a resulting 'difference tone'.

[southernyahoo]

The account by bipedalist contains mention of a high pitched sound "occasionally a sound such as someone running their wet finger around the rim of a wine glass " .

In general, "screams like a woman", and such are notoriously high pitched, also testify to high pitched emissions.

Antfoot, you are correct that there is no absolute proof of the association, nonethless, the temporal and spacial correlations are high enough to be presumptive. Given the large size of BF, direct emissions of infrasound is a possibility, and, heretofore has been the default assumption. However, the physics of sound emission argues against efficient emission of infrasound. Efficient emission seems necessary given the large effect the fluttering or infrasound has upon people.

I thank everyone for their comments. What is needed is an experimental record of the phenomenon. Given the rarity of meeting a BF, few people are likely to have suitable equipment with them. Bipedalist, given what I know about his situation, is one of the few people for whom it might pay to construct and carry suitable recording apparatus.

I hope to later publish on this thread a block diagram of a suitable recording apparatus.

Put your headphones on spurfoot.

Here is a wood knock recorded at close range while researching. You will hear a high ring tone just before and after the knock. We never heard the ringing but did hear the knock. This was recorded using a home built parabolic dish.

Wood Knock 9-29-07.mp3

This filtered version may be a little easier to hear.

filtered-knock.wav

Don't get me to speculating about the flutter sound ....

[Guest spurfoot]

sy, my aged hearing is so bad there is little chance I could directly perceive what you wanted me to perceive. Nonetheless, something did appear on the iTunes spectrogram when I used that software to play it back. Thanks a lot. Most of the comments so far seem to support the hypothesis, now you have evidence.

It all makes sense from a physics standpoint. Infrasound is difficult to emit efficiently. High pitched sound is easy to emit. It is essential that the ears of the listener be non-linear, otherwise the difference interference between the two high pitched tones will not be created in the perceptions of the listener. Apparently that is true of human hearing judging by the comments of the musician above. The mathematics of hetereodyning are well understood. The principle is routinely used for design of radio receivers.

If anyone has more relevant recordings, let's hear it, or, in my case, spectrogram it.

[Guest BFSleuth]

Heterodyne is a new one on me. I found this, which gives some idea to those of us that haven't experienced it:

I also notice that there is a lot of research into heterodyne sounds from bats.

[Guest BuzzardEater]

BFs whistle. That's reported more than once.

Isn't there some sort of whistled communication in the Andes? It pierces fog, no?

[bipedalist]

Heterodyne is a new one on me. I found this, which gives some idea to those of us that haven't experienced it:

I also notice that there is a lot of research into heterodyne sounds from bats.

Whole lotta shaking going on there (err I mean fluttering); plus the visuals were pretty good experimental film in their own right.....

some of the bass sounds I've heard/felt have taken on that type of rhythm...... not as much the higher frequency sounds that I've studied to date though......

Here's some good ultrasonics of an Italian bat, which has alot of interesting ascending/descending segments, and some of the following are based on heterodyning principles:

http://soundcloud.co...ltrasounds-bats

Mexican bats: http://soundcloud.co...trelli-palenque

And the whole collage: http://soundcloud.co...ts/ultrasounds/

Edited February 14, 2012 by bipedalist

[Guest]

I find this topic interesting as a player of the great highland bagpipe. It has been theorized (though not tested, that I know of) that the combination of high and low pitched sounds coming from the pipes has some infrasonic/ultrasonic, (even just sonic?) affect on other animals (people, horses). Meldrum mentioned it in LMS. May pertain to what you are talking about. What BF is purportedly cable of seems mostly out of human range of hearing. Perhaps not completely?

I'm a fifer, and you can clearly hear this in a duet. The over and undertones are easily produced on fifes, simply play anything and have a partner play along using a fife that has a slightly different construction. Contributing factors include differences in tone holes, sounding length, embrochure, cork placement and of course gross pitch changes caused by technique differences between the player (roll out, roll in) and this is certainly prominent in flutes, though flutes are too standard in construction, most times you won't hear this occur in a band-like setting. The problem, the more fifes play, the less pronounced the effect.

You can hear the two original tones, plus the undertone, plus a pulsing tone that cycles way way down low. Think of the harmonics of airplane engines in flight. If they're not perfectly synchronized, there's a hum that rolls around the cabin like a steel ball rolling around a bowl.

I wonder how faithfully this would be recorded? I am actually producing a recording this Wednesday for other purposes, maybe I'll set aside a few minutes to explore it.

[Guest BFSleuth]

Barlow, when you do your experiment you might be able to capture how the sound pattern looks. If you place a loudspeaker face up with a waterproof layer (like cello) and fill it with water, when you play it back you can see the patterns created by the sound. Take an HD video of the effect and post it if you would. Could be very interesting.

[Guest spurfoot]

If the ultrasound (or just high pitched) heterodyning is true, then the question arises of where does the sound physiologically originate ? In that double rows of teeth have been reported for BF, perhaps a whistle in the gap between two rows of teeth might be the mechanism with fluttering of the tongue modulating. Alternatively, perhaps vocal chords are capable of it. Still another alternative is that a specialized structure does it. All this presupposes that the fluttering is ultrasound heterodyning (or modulation).

My friend "John Whorfin" has had extensive field experience with the phenomenon and he believes it is actual infrasound. He and bipedalist should get together with electronics expert Wally Hersom and look into it with a critical experiment. I'm hoping "John Whorfin" will comment on this thread. He is currently having computer and weather problems out there in the boonies.