Scientists discover mechanism of hearing
news.ohsu.edu
news.ohsu.edu
Human hearing can distinguish thousand of individual frequencies, with the highest frequency 1000x the lowest.
Human sight can distinguish 3 broad frequency regions, with the highest frequency 2x the lowest.
Where vision shines is distinguishing where the signal comes from.
Suggest closing your eyes and having someone else snap their fingers around you, you'll know immediately where that sound came from. This is accomplished by your mind differentiating the slight time difference between when your left and right ear register the noise as well as the volume difference.
This innate ability can be developed by DJ's to take two songs playing at different speeds and speed or slow them down to match. This is called "beat matching" and before software made this more accessible (aka more automated) it was the key skill necessary for DJ'ing as it allows seamless transitions between songs.
I still find your comment insightful and interesting, I just had to nitpick that one part.
Cheers
A many-channel sense with full frequency, phase, polarization, ... information would presumably be very hard to process usefully.
That would be very difficult to accomplish electronically.
(I did an Anatomy degree almost 20years ago now, all from memory)
The FFT is a specific mathematical construction that carries out a Fourier Transform efficiently through a hierarchy of "butterfly" steps. The ear has no such thing. It is just ~20,000 hair cells, each resonant to a specific frequency. That is, each computation is local, very unlike the FFT.
I can roughly recall the mechanism by which it worked, and was told that this was an analog for how the Fourier transformation worked, and I vaguely remember going through one on paper. The spiral of the cochlear seems an analog of how the harmonium works. Does the earlier poster have a point with regard to the cochlear as a physical object performing a Fourier transform (though perhaps not a fast one)?
Folks around here don't handle ambiguity well, and are treating your comment like it's wrong, rather than basically correct except for a harmless conflation of an algorithm for something with the thing itself.
Ah well.
> sinusoidal frequency domain decomposition of sound waves is a key mechanical phenomenon exploited by our hearing system, leading to in effect a frequency domain transformation of the temporal pattern of compressions and rarefactions that we term sound. https://uncommondescent.com/video/hearing-the-cochlea-the-fr...
That one has a video.
Your case is roughly as incoherent as one which claims that a thrown ball does not perform Newtonian physics. It doesn't have to.
Now that we've disposed of the nonsense that cochlear response is not meaningfully modeled with Fourier analysis, interested parties might have fun with research into all the ways this model is not perfect. I've got a paper loaded in my reader claiming it's actually wavelet analysis, for when I have time and inclination to read it.
You are right. My apologies for the conflation.
I wonder about the limits of the muscles of the eardrum (TT and stapedius) to prevent hearing damage. For example, I recall awaking one morning being unable to hear because those muscles were isometrically flexing to a degree that prevented the eardrum from move normally. I thought I lost my hearing but then they started to relax over a few minutes.
I don't know if anyone else can, but I can consciously make both eardrums vibrate creating a sound like a rumble.
Last thing: I can hear my left eye move. I have a SCDS that I was able to identify myself as it's the only condition with this rare symptom. There is a tiny hole in the thin, porous bone between my inner ear and brain. It can be fixed surgically but requires brain surgery that effectively jacks the brain up and out of the way to be repaired by a surgical otolaryngologist. Eating chips is horrendously loud. Exercising leads to hearing my pulse. The risks of surgery though make me think it's worth enduring annoyances, although I don't know if it's causing extra cognitive load (distraction filtering) or balance problems. Oh and tinnitus from hell.. REEEEEE.
I remember listening to a podcast where one of the guests experienced a highly stressful event. They mentioned that they felt like they couldn't hear anything for a few weeks but the problem eventually went away.
When I heard this, I assumed it was some kind of psychosomatic effect but reading this made me realize that it could also be related to actual physiological responses to stress. (You could argue that psychosomatic responses are also physiological so I'm drawing a distinction between "your brain stopped you from hearing" vs "your body was so stressed out, your ears stopped you from hearing".)
The human body is amazing.
I can as well when I consciously try to pop my ear drums.
“ Inside the ear is a small muscle called the tensor tympani. When this muscle is tensed, it causes a roaring or whooshing sound in the ear.”
Although a rumble seems a better way to describe the sound.
This reminds me of an article that I once read (couldn’t find it, but I believe it was about [1] - Quest for Zero-Decibels).
In absolute silence, all sorts of bodily noises crop up - your heartbeat, creaking bones and muscles, popping noises, etc.
[1] https://www.goodreads.com/book/show/7932161-zero-decibels#
Or did we think we understood it the whole time, but only just recently discovered that we actually didn't?
What the researchers are reporting appears to be a more detailed structural description of this sensory protein complex, and the additional structure information combined with simulations of known physics and chemistry in turn suggests additional detail about of how the "signal" occurs on the molecular level.
Disclaimer that I didn't take time to read the whole thing now, but that's the gist of it from summaries and skimming.
It is, with little doubt, some valuable pieces of information in the context Collective Knowledge of Mankind, and keeping large, complex, multipart molecular machines like this reasonably stable and normal for examination is arduous work, so I don't mean to denigrate the studies or the scientific paper, but as so often the way this is being spun in the press release is regrettable.
According to the article and the paper we now have a clear understanding of how it works - the proteins in worms (which are similar to humans in their hearing structures) and their function.
So, unless I misread it, we absolutely know how sound > neural impulse works.
More:
> The initial step in the sensory transduction pathway underpinning hearing and balance in mammals involves the conversion of force into the gating of a mechanosensory transduction channel1. Despite the profound socioeconomic impacts of hearing disorders and the fundamental biological significance of understanding mechanosensory transduction, the composition, structure and mechanism of the mechanosensory transduction complex have remained poorly characterized. Here we report the single-particle cryo-electron microscopy structure of the native transmembrane channel-like protein 1 (TMC-1) mechanosensory transduction complex isolated from Caenorhabditis elegans. The two-fold symmetric complex is composed of two copies each of the pore-forming TMC-1 subunit, the calcium-binding protein CALM-1 and the transmembrane inner ear protein TMIE. CALM-1 makes extensive contacts with the cytoplasmic face of the TMC-1 subunits, whereas the single-pass TMIE subunits reside on the periphery of the complex, poised like the handles of an accordion. A subset of complexes additionally includes a single arrestin-like protein, arrestin domain protein (ARRD-6), bound to a CALM-1 subunit. Single-particle reconstructions and molecular dynamics simulations show how the mechanosensory transduction complex deforms the membrane bilayer and suggest crucial roles for lipid–protein interactions in the mechanism by which mechanical force is transduced to ion channel gating.
Sight came way, way, way, way, way, way, way later. Encoding language in sounds is an even more recent innovation, in the grand scheme.
This may also be why we have such trouble assigning words to smells, and you can't write a poem to replace a hug, for instance. They're processed by entirely different, and far more primal, parts of the brain than language.
OTOH, detection of mechanical vibrations seems like the kind of adaptation to evolve early. Hearing is in some sense just a refinement of that, so at the very least the groundwork for it must be old.
Am I being unclear?
I asked : did we always consider it to be a mystery? Or did we have a different model before? (Which just recently got replaced by this new, better, model)