Infrasound Inquiry: Newsletter Challenge (November 2018)

middle "C" = 261.626hz each octave lower the "C" is half the frequency of the preceding "C"...

one octave lower = 130.813hz

two octaves lower = 65.406hz

three octaves lower = 32.703hz

4 = 16.351hz

5 = 8.1755hz

6 = 4.08775hz

7 = 2.043875

8 = 1.0219375

9 = 0.51096875

10 = 0.255484375

11 = 0.1277421875

12 = 0.06387109375

13 = 0.031935546875hz

You are correct that an octave is half (or double) the original frequency. I trust your numbers. So 0.03Hz is what the New York Times says a bird can hear. Sure looks like fake news to me! I would expect a smaller animal to have a higher pitch of hearing than a bigger one. Elephants are known to hear lower notes than humans (but no where near that low!)

One cycle every 32 seconds or ~ 1/32 Hz. That "sounds" kind of hard to believe.

Astronomers say they have heard the sound of a black hole singing. And what it is singing, and perhaps has been singing for more than two billion years, they say, is B flat — a B flat 57 octaves lower than middle C.

New York Times, 2003

If the ripples are pressure (sound) waves moving at constant speed (about 1170 km s⁻¹ for a temperature of 5 keV) then their separation (wavelength) of about 11 kpc means a period of about 9.6 × 10⁶ yr.

Andrew Fabian, et al., 2003

https://physics.info/music/problems.shtml

I bet them pigeons can't hear that low!

Didn't hear that coming....

Seagulls are the pigeons of the beach...

The Dolphins maybe can, and according to Douglas Adams they will leave the planet before the bang. But then who tells us what pigeons can hear or not hear?

My last conversation with one was very one sided and went like: "Dear P. out of my way, kick slosh, ice cream on shirt, shade, missed it, bye bye!"

My last conversation was Chuck...Chick...…..Boom

This is just under two cycles per minute. The second hand of an analog clock is an octave higher in pitch. How in the world did they come to the conclusion a pigeon can "hear" this low of a pitch? A pigeon may feel the swaying of the cable they are perched upon at this slow of a rate.

Can't see the whole article, but this is the paper that found that pigeons have infrasound abilities. Looks like the researchers used heart rate changes as a measure of sensitivity.

https://link.springer.com/article/10.1007/BF00679906

What I read in the abstract does clearly indicate a hearing response. I wonder if this is related to in flight navigation by passive sonar. Hearing an approaching wall or heavy branch before flying into it would certainly be a survival advantage.

Why is it necessary to check back in a week for the answer , If someone gets the correct answer right away, wouldn't it be prudent to give credit where credit was due and move on to the next question ?

The answer to the question is correctly given by SolarEagle in #1, this accompanied by sufficient citation.

The various sub topics, for me, remain unanswered.

I find there is a study that proposes the Homing Pigeon uses the ULF tone as a long distance navigation aid: https://en.m.wikipedia.org/wiki/Homing_pigeons

Thanks buddy, for validating my appraisal of SE.

I wonder how the pigeons who participated in the experiment felt about this part? "Surgical removal of middle ear or inner ear structures reduced or eliminated the infrasound responses." How did they find their way home after the tests?

tonyhemet,

"Why is it necessary to check back in a week?" Because those are the rules.

redfred, Any idea why birds fly into windows, and not walls? Maybe we humans don't hear them when they fly into walls?

Well if my idea that infrasound helps in flight navigation (a big if) the infrasound tells them there is something in the area to avoid but the clear glass wrongly implies this is a passageway between the obstacles.

additionally, as glass has a higher frequency then the wall it will give a false variance between the two surfaces

I have bird feeders outside my living room and kitchen. Both have large windows so that we can watch them.

Immediately behind the windows are wooden blinds, closed when we aren't watching them.

Birds regularly fly into these windows when the blinds are closed.

I haven't tried to do the math, but the speed of sound is well known, and at a frequency of 0.031935546875hz, I think the bird who is going 120 FPS is going to hit that window, or tree, or building before it can change direction if it is relying on the sound for collision avoidance.

Just a thought.

The period of time for 0.03Hz is 33 seconds for 1 cycle. It's much too long for navigation of birds. My first house had a large window on the west and a glass patio door on the east with no walls between. Birds would regularly fly into the window when both curtains were open. No bird ever flew into it during the 7 years I lived there when either curtain was closed (that blocked the VIEW of the trees on the other side).

Yes. I think they navigate by sight.

The (many) birds at my place, when startled, all take flight at once. Some go the wrong way.

How many of those birds were pigeons?

Now that you mention it, I don't know that any were.

Doves maybe.

Apparently, there is some evidence that pigeons use infrasound for navigation:

From NASA,

"Could sound or electromagnetic disturbances affect homing pigeons sense of direction as well? The answer seems to be yes. New findings point to noise from jet engines for being responsible for the pigeons erratic flight. In the journal New Scientist, it was revealed that not only direct engine noise but supersonic shock waves produced by the Concorde may also interfere with frequencies the pigeons sense for long distance navigation. It has been suggested before, that for navigation purposes, some birds may utilize low-frequency sound waves (infrasound) that they can hear but humans can't. These waves may be generated by the simple rumblings of water hitting land, for instance, which then radiates infrasound into the air. Perhaps the birds use infrasound as a kind of mental chart, relating their starting point to their destination (home). Their home site would have a unique infrasound signature that they may be able to hone in on."

https://web.archive.org/web/20041102004955/http://pao.gsfc.nasa.gov/gsfc/educ/science/2000/04-07-00.htm

It has been suggested that humans have a sensitivity to infrasound, which generates a feeling of unease. One theory is that "haunted places" might be locations where wind currents generate infrasounds like an organ pipe.

https://en.wikipedia.org/wiki/Infrasound

As for birds colliding with windows, I would doubt that it has anything to do with infrasound. The wavelength of sound is about L=1000/f, where L is in feet, So infrasound should be diffracted around most house size structures. I'm pretty sure birds see a reflection of the sky. (We have a cardinal that sees his own reflection and has been fighting with himself for a few weeks now.)

Navigation, directional, is different from detecting objects in your path....It just tells you which direction to go, not the path to take...

Lyn, I looked for that rule, I couldn't find it.

I figure like the rules of Monopoly, if you land on Free Parking, you get all of the loot in the kitty.

"Check back in a week for the answer, right here on CR4."

When does Sound stop becoming a sensory perception related to Hearing and starts becoming a Pressure wave which is not heard, but Felt?

I have been through 3 major earthquakes, the last being the Los Angeles Northridge quake.

At the time , I lived at the mouth of the Big Tujunga Canyon, which acted as a large speaker.. Prior to the shock wave hitting the house, a "pressure wave" ran through the house which was felt before being heard. Then it became very loud as he wave started moving objects in its vicinity. An Structural Engineer told me later that all the damage in earthquakes are caused by sound waves, resultant from the slippage of the plates, moving the strata.

I think your SE was confused.

Sound that you can hear is the result of, and not the cause of damage.

The slippage of the plates, moving the strata, and the resulting rapid physical movement of the Earth and things (houses) on it cause the damage.

Just for fun, I threw this ⇓ in. We're OT anyway.

ahem...

It seems no one knows about infra-sound sound that elephants make ???? Not to mention Sasquatch Science says it cant be proven ! But the gov knows all about this ! just look at all the disappearances at Yosemite national park in Ca. just for one example ! as well as all across the USA hmm makes one wonder don't You ?

Take Care out there

I mentioned Elephants in post #9. I don't get the rest of your post. If you have Sasquatch evidence, start another thread.