Talk:Cochlea

Old stuff not in a section

I have just added a bit more detail, but unfortunately I seem to have messed up the links to the organ of corti page and cant get it right - can anyone help? Povmcdov 20:17, 25 Apr 2005 (UTC)

fixed it myself now, I didn't realise links were case sensitive! Povmcdov 19:22, 29 Apr 2005 (UTC)

Have just added formatting and I intend to expand this article significantly - anybody else want to help? I will complet frequency discrimination within 12 hours hopefully, but feel free to add and edit (as always!) Povmcdov 20:28, 29 Apr 2005 (UTC)

Is there any man made device which separates frequencies? The monochromator and the electronic filter look so totally different. --Arnero 12:38, 28 December 2005 (UTC)

Yes, the spectrum analyzer is a tool used in electronics to do so. And the Fast Fourier Transform (its a computer algorithm, but I guress it's a manmade device)--mcrema

The spectrum analyzer - according to its page - can only "hear" one frequency at a time. The Fourier Transform requires multiple, discrete steps, but there is only one cochlea and only this single mechanic channel connects the different frequency regions. It seems that no wave effects take place.

>> tuned to certain sound frequencies,

Mechanically or chemi-mechanically? --Arnero 16:27, 22 February 2006 (UTC)

In my experience a spectrum analyzer can measure energy over a wide range of frequencies. It only measures one frequency (actually one small frequency band) at any instant, but it sweeps across the specturm of interest very rapidly, so the eye cannot tell the difference. Perhaps this is not true for all models. The cochlea is often (qualitatively) compared to a specturm analyzer in hearing texts (if this is what you were getting at with your question), and it would be appropriate to make this comparison on the cochlea page.

Your observation of "no wave effects" leads some interesting (current) confusion. At first, the operation of the cochlea was thought to be resonance (by Helmholtz). This position was re-evaluated (by Bekesy) and for many years the effect was thought to be the so-called "traveling wave". Recently the resonance theory has resurfaced (Zwislocki) but you still see it described both ways. For the purposes of a brief introduction such as this article, either description is probably fine.

A good "quick" review of place-theory can be found in the first few pages of this document

http://www.utdallas.edu/~loizou/cimplants/tutorial/

A more detailed but excellent review can be found here:

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1464757&dopt=Abstract

I can recommend others if you like.--mcrema 22 February 2006

PS. Clearly, another man made device which separates frequencies is the cochlear implant.

Moving content here

Unless there are any objections, there's some content at Inner ear which I think would better belong on the cochlea page. --Arcadian 00:59, 20 February 2006 (UTC)

The semicircular canals are part of the Inner Ear but not part of the cochlea.--mcrema 22 February 2006

References

I removed a recent ref and speculation because it appears to be someone promoting their own recent narrow work. I added a sources tag because we really need to make a reference section and reference the various claimed facts. If someone was to work on this, their contributions of recent narrow stuff might also be viewed in a different light. Dicklyon 18:36, 21 January 2007 (UTC)

Too technical?

I think the scientific terminology is a bit overused here. I (college undergrad, engineering) could read the article and just about understand it, but only with the mouse in one hand and Websters in the other, particularly of issue was the technically correct, but non-vernacular use of "superior" and "inferior". I might have a go myself tomorrow. Tiggythegreat (talk) 01:43, 11 May 2008 (UTC)

I don't think it is too technical, but it isn't well explained. For instance the sentence "It makes 2.5 turns around its bony axis". Presumably the editor meant to say that the organ is spiral shaped, making 2.5 turns around its (bony) axis. —Preceding unsigned comment added by 124.197.15.138 (talk) 19:50, 13 February 2011 (UTC)

I clarified the first sentence based on the last poster's suggestion. Removing the Too Technical template since no one has really concurred; after reading the article, I don't see how it can't be understood by most people. Anyone who needs a general understanding of the cochlea's purpose will most likely not have a hard time understanding it, and anyone needing to know more details will more than likely already be able to understand the more technical language. Any objections, feel free to revert, since this is just my own perspective. AryconVyper (talk) 04:33, 14 February 2011 (UTC)

Cochlear Microphonics?

Are cochlear microphonics present with bone conduction stimulus? Speculation osprey (talk) 18:30, 10 July 2008 (UTC)

Misspelling

The main image of this article, Cochlea-crosssection.png, has the scala tympani misspelled as scala timpani. This image is also on the "scala tympani" main article. Can anyone fix this? Mmerlo (talk) 18:08, 16 September 2008 (UTC)

Done. I used the closest font I could find, Helvetica. Dicklyon (talk) 04:06, 17 September 2008 (UTC)

Contradiction between picture and text?

In the section "Comparative physiology", it is stated (last statement of the section) that "One unavoidable difference, however, is that while all hair cells are attached to a tectorial membrane in birds, only the outer hair cells are attached to the tectorial membrane in mammals.". However, in the picture "Cross section of the cochlea" (File:Cochlea-crosssection.png), the inner hair cells are also attached to the tectorial membrane. Is there a mistake in either the picture or in the text? Shengchao Li (talk) 19:46, 3 December 2009 (UTC)

How many turns?

Does the cochlea make 2.5 turns or 2.75 turns? The article asserts both. John Link (talk) 02:24, 15 November 2014 (UTC)

This book says 2.5 to 3 in humans. Dicklyon (talk) 04:45, 15 November 2014 (UTC)

Wikipedia articles fail to explain the basic workings of the human auditory system.

My frustration isn't just with Wikipedia articles. I have read dozens of Internet articles and watched numerous videos attempting to explain the human auditory system, and every one of them skips over a simple explanation of the path that sound waves take after they enter through the oval window of the cochlea. This "path," as I'm describing it, gets even more fuzzy once a tutorial starts talking about bending stereocilia, potassium ions, spiral ganglions, and neurotransmitters. The sequence of those particular events is easy enough to follow, but the big question of the path that the original sound information has taken is left out. The article on this Wikipedia page concerning the cochlea has been criticized for being too technical, but that, as I see it, is not the problem. The problem is, it's vague and subjective and leaves important basic questions unanswered.

The first and most elementary question is: what path do the sound waves take to reach the basilar membrane? Nobody answers that question. I have searched the various online encyclopedias, medical websites, university publications, scientific papers, etc., and they all skip over the question and only offer a vague, generic explanation, such as "sound waves entering the cochlea cause the basilar membrane to vibrate." It should be obvious that isn't an adequate explanation. The only source I have found that attempts to answer the question is a YouTube video titled Auditory Transduction (2002).[1] According to that video, sound waves traveling on an upward course through the scala vestibuli cause Reissner's membrane to vibrate, and that causes vibrations in the endolymph fluid of the cochlear duct (scala media), and that, in turn, causes the basilar membrane to vibrate. In that description, the sound vibrations are coming from "above," relatively speaking. But if you look up Reissner's membrane as a separate subject on Wikipedia or anywhere else, it says nothing about sound waves passing through Reissner's membrane into the cochlear duct and impacting the basilar membrane. The articles just say that Reissner's membrane serves to separate the fluids of the cochlear duct from fluid in the scala vestibuli. Even so, that explanation seems more reasonable than the alternative, which would be for sound waves to ascend upward through the scala vestibuli to the apex, then descend down though the scala tympani before impacting the underside of the basilar membrane. There are a couple of difficulties with that possibility. For one thing, there is a membrane at the apex of the cochlea called the helicotrema. It's not clear the degree that the helicotrema is porous. Does it allow the free flow of fluid? The other thing is, I have read that fluids in the scala vestibuli and scala tympani are somewhat different (not to be confused with the endolymph of the cochlear duct, which is potassium-rich). If the fluids are at all different, that would seem to indicate that there is not a continuous, unimpeded flow between the scala vestibuli and the scala tympany and that the helicoteama is something of a barrier. In the scenario described in the video I mentioned, sound waves entering at Reissner's membrane pass through the cochlear duct and end up in the scala tympany, where they continue their journey to the round window.

In addition to questions about the "mechanical path" that sound waves take to reach the basilar membrane, there are questions about the "transduction path" -- i.e., how mechanical energy gets transformed, or transduced, into nerve impulses. This gets skipped over in most of the articles I have read on the Internet. What the articles do explain is this: Movement in the basilar membrane causes stereocilia hairs to rub against the underside of the tectorial membrane, which bend the stereocilia and open up channels that allow an influx of positively charged potassium ions to enter hair cells. What is confusing about that, first of all, is that there seem to be two sensory devices: the basilar membrane, and also the stereocilia. Are they tuned to the same frequency?

What puzzles me is how mechanical information about a particular sound, once it is received by the basilar membrane or stereocilia hair, makes its way to the auditory nerve. Do potassium ions carry the sound waves deeper into the hair cell? From what I understand, a depolarization effect opens up channels in the hair cell wall, which allows sodium ions to enter. And that triggers the release of neurotransmitters. Do the neurotransmitters take up information about the sound waves? Where exactly are the neurotransmitters getting sound information from? There must be a number of players, like runners in a race passing a baton one to the other.

The path that mechanical ("sound") information takes becomes an electrical path and finally a neurological path. But it's certainly one, continuous path. What seems to be missing in all the explanations is a map of the course that the sound vibrations take with no segments left to the imagination. If there is an explanation in the Wikipedia articles that I have missed, I would be appreciative if someone would guide me in that direction. Otherwise, I would hope that someone who has the answers (and isn't just guessing) would update the Wikipedia articles in question and provide some references to materials that I can study to further my knowledge.

2600:8801:B011:300:A15D:DD06:EA71:2279 (talk) 18:30, 11 February 2021 (UTC) James.

Reference (1): "Auditory Transduction (2002)," YouTube video.

Suggestions for rewrite

While I appreciate the effort that has gone into writing this article, it did not really tell me in any detail what I expected to learn: what does the cochlea do and how does its parts "work together" to achieve this (and does it really do Fourrier transforms?). I believe this article would be more informative and easier to understand if it began with a large-scale overview of the functioning of, and interplay between, the different parts of the cochlea. The items in the list already provided under the heading "Structure" could be expanded to explain what each part does in relation to the others. The information contained in the section on "Function" should be presented before all the "anatomical" detail, and the overall introduction to the article should focus on what the coclea does rather than its structure.

Henrik Thiil Nielsen (talk) 23:05, 25 October 2021 (UTC)