Topological acoustics are popping up in Nature and Science, is it really useful?
Traditional absorption, transmission and reflection applications are very useful, are they interesting enough? If not, how can we make them interesting again?
Would like to hear more opinions from everyone?
Thanks
It really depends on what you define as interesting or cool. There are a lot of fascinating areas in acoustics including the design of metamaterials (these are also applied to deviate earthquakes from critical structures), acoustic levitation and ongoing projects on the use of acoustic waves for the generation of Mach effects in the field of space propulsion! Personally, I have an interest in the construction of acoustic and ultrasonic devices therefore I find very interesting everything that concerns aspects of the production of acoustic sensors and the performance enhancement. In this field, lot of work is going on in the area of subwavelgth measurement and the development of one pixel acoustic cameras.
Reflection measurement are definetly of interest and in constant evolution, have a read to some tribo-acoustics papers for the measurement of friction, load and engine oil in-situ in running engines :)
Michele,
Thanks for your reply. Michele Schirru
You mentioned quite few of interesting topics, such as design of metamaterials, and acoustic levitation. I think I really like these two.
I found low frequency sound absorption (or shielding) is very challenging, but not well tackled yet. They are very useful in daily life.
Let's keep the discussion going.
Thanks!
Best,
W
Health Effects of Wind Turbine Noise: https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20090026531.pdf
http://www.canadianaudiologist.ca/issue/volume-2-issue-3-2015/column/other-peoples-ideas/
Auditory Hallucinations https://hearinghealthmatters.org/hearinginternational/2019/working-with-tinnitus-is-more-than-masking/
https://www.ncbi.nlm.nih.gov/.../PMC3969291/pdf/main.pdf
Hi Wan,
In the area of Bioacoustics, there are many interesting, unsolved problems. One on which a great deal of effort is being expended by many auditory neuroscientists is the unraveling of the molecular and cellular basis underlying auditory transduction. Transduction is the changing of energy from one form to another. In the mammalian inner ear, this is accomplished by the inner hair cells which transform the mechanical shearing force applied to the hair bundle at the apical surface of the hair cell into an electrochemical force in the form of a receptor potential measured across the hair cell membrane. Exactly how this force arrives at the hair cell, the proteins and molecular scaffolding responsible for opening and closing ionic channels responsible for generating the receptor potential and the elucidation of all the modulators of these processes are being scrupulously studied in many labs around the world.
Hope this helps-
Peter
Hi Wan,
Another interesting and important problem in Bioacoustics concerns the elucidation of the cellular and molecular events mechanisms underlying the cochlear amplifier (CA). Understanding this "amplifier" will surely be a major breakthrough in understanding hearing. The CA is responsible for increasing the sensitivity and the frequency resolution of the hearing organ. It does this presumably by taking advantage of the electromotility of the outer hair cells (OHCs) in the Organ of Corti which act as tiny motors that feed mechanical energy back into the basilar membrane (BM) traveling wave at precisely the right moment and essentially "sculpt" the BM displacement pattern. The result is that the max. displacement of the BM is greater (the "amplifier") and narrower (improved resolution). One of the remaining key unknowns is the mechanism underlying the exact timing of the electromotile responses of the OHCs: i.e., how do the OHCs at the BM displacement peak "know" when to expand, and how to the OHCs on either side on the displacement peak "know" when to contract to achieve proper sculpting of the traveling wave and thus proper functioning of the CA?
All the best,
Peter
Hi Wan,
I have been thinking more about your question. Another fascinating problem in bioacoustics is to elucidate the factors (the evolutionary selective pressures) that have shaped and sculpted animal communication signals. For example, there are frogs in Borneo and China that communicate using ultrasonic (>20 kHz) frequencies. This frogs inhabit the vegetation along rapidly flowing mountain streams. It has been discovered that especially after torrential rains, these streams produce high levels of broadband noise covering the entire human auditory spectrum (up to 20 kHz) and it is virtually impossible, for example, to have a conversation near these streams. So, over evolutionary time, these frogs have raised the frequency of their calls above the background noise (into the ultrasound) to communicate.
Peter
Hi Wan,
On a related issue, Slabbekoorn and Peet (Nature, 2003) found that urban populations of the European songbird- the Great tit (Parus major)- sing at higher frequencies than populations of this same species living in quieter, rural areas. They concluded that the urban birds raised their call frequencies in response to the predominantly low-frequency background noise in the city. This is another example in which anthropogenic (human-generated) noise can affect animal communication signals.
Peter
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