Infrasound - Science topic

Dear Anders Buen.

Now about the main thing.

Comment #2.

My colleague Boris Kapochkin has already written that sound can travel several thousand kilometers underwater when theory says that 200 km is the maximum.

I calculated that for cylindrical sound propagation with a frequency of 2 Hz at a distance of 200 km, the transmission loss is 67 dB (the power of sound energy decreases by about 200 thousand times), and at a distance of 5000 km, the transmission loss is 53 dB (the sound power decreases by more than 5 million once). This is fully confirmed by the results of calculations by my colleagues from the Odesa Department of Hydroacoustics of the Academy of Sciences of Ukraine 3A%2F%2Fhydromech.org.ua%2Fcontent%2Fpdf%2Fcons%2Fcons2005_084-089.pdf&usg=AOvVaw0vDKOK1EACZ2j4ciY0u2iB).

In order to travel 5000 km, an acoustic wave must continuously, at each cycle of compression and extension, receive energy from the aquatic environment. Otherwise, only 200 km. I need to voice a few postulates.

First postulate. Water has structure. I have attached several diagrams in one picture.

Second postulate. When breaking and restoring one broken intermolecular bond, 400 kJ/kg is absorbed and released for every 10 water molecules. That is, during compression, the structure of water is destroyed, and the speed of sound in such a medium increases. The measure of the kinetic energy of the medium must increase (the process of wave propagation is non-adiabatic).

Third postulate. For infrasound, the process of wave propagation is adiabatic.

Fourth postulate. The destruction of the structure of water requires disproportionately less time than its restoration.

In this way, the aquatic environment, in the process of exposure to infrasound, releases energy and reduces the total mass of associated molecules. As a result, positive feedback occurs, which is very rare in non-biological phenomena, and is aimed at reducing entropy.

It's about like this somewhere.

Thanks, Vadym. Any ideas about how far away one must be to avoid the effects of the wind turbines?

Peter

The individual and public health hazard aspects of infrasound have been extensively researched. The hazards have been specifically linked to frequencies and amplitudes that were explicitly identified. Perhaps such hazards overshadow the healing effects. It is reported that every human being's metabolism uses body-generated infrasound for normal health. So it is quite plausible that future research can identify specific spectral characteristics of infrasound that heal.

Jun Lv

Did you observe and responses on the infrasound system during the actual event of the earthquake?

I am so curious about the 4 day delay between the infrasound event (which certainly looks real to me). Is there some chance that this data was actually from the day of the event?......very interesting.

Thank you for your words.

Our current focus has been on loudness, since not even this measure has been studied in much detail below 100 Hz. It turns out there is a region of locally increased sensitivity between about 35-50 Hz. Some people seem to be more sensitive than others to specific frequencies in this range (which perhaps can help to explain large individual differences usually reported), while below this region only relatively high sound-pressure levels are heard. However, there are apparently other perceptual effects particularly associated to infrasound, such as modulation of higher frequencies, which also play a role. While we know the topic is complex and broader, at the moment we seek to establish basic sound perception attributes of low-frequency and infrasound (by means of psychophysical methods).

What is your band requirement ?

What is the medium (air, water ...) ?

You can take a look to Bruel & Kjaer products, they are expensive but they are viewed by many as the best transducers (at least in my field, underwater acoustic).

For the acquisition device, poor chance a sound card (even a high-grade one) can do the job because they won't pass DC to 20Hz, 50Hz or 100Hz. The lowest I've found are from the RME brand, they are  advertising 5Hz at -3dB , and i've measured mine wich cuts at 1 or 2Hz.

That said, another culprit of doing acquisition with a sound board is if you need to synchronize the start of the recording session (no trigger input).

Please be aware that, historically, religious chants have used low frequencies for production of alpha wave states. In particular I would suggest examining Tibetan Buddhist chant e.g. the Gyoto Monks.

or then there's Charlie Watts and Bill Wyman :-) same thing however.