N.Wells
Posts: 1836
Joined: Oct. 2005
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You have a golden opportunity here, Gary. I don't know enough about laryngeal anatomy and sound production, and it's possible that there's some odd relationship where a lag in signal arrival time could have some bizarre but significant effect on infrasound production. I've no idea what that could be, but you have a great opportunity to make me look like an idiot and make yourself the expert with credibility. But here's the thing: you can't just say, "might be", or make an empty assertion: you have to back up your suggestions and assertions with solid facts.
Anyhow, the more I read, the more it seems like you have less than no idea of what you are talking about. Sound production is primarily the job of the larynx, except in birds, and it happens in the larynx, sometimes beside the larynx, and above the larynx, but not below it. Since the length of the neck is below the larynx, the length of the neck and the length of the recurrent laryngeal nerve ARE NOT in any direct way related to the vocalization, except that sound is produced by the air that has come up through the neck from the lungs. The trachea is not a "resonance chamber". The length of the neck and the recurrent laryngeal nerve are not inherently proportional to any resonating chambers, contra your assertions.
From Wikipedia: Sound is generated in the larynx, which manipulates pitch and volume. "Fine manipulation of the larynx is used to generate a source sound with a particular fundamental frequency, or pitch." The sound is modified as travels past the tongue, lips, mouth, and pharynx. Pitch can be modified by rocking the thyroid cartilage forward and backward on the cricoid cartilage, by manipulating the tension of the muscles within the vocal folds, and by moving the arytenoids forward or backward. The vocal apparatus consists of the false vocal folds (which are used for vocalization only in Tuvan throat singing and the like) and the true vocal folds (folds). Some animals have resonating chambers consisting of pouches or ventricles or sacs or other diverticula off to the side of the larynx, which can be used to make additional sounds.
| Quote | | [from ]http://scienceblogs.com/tetrapo....po....] So far in this series of articles, we’ve looked at primates, baleen whales and reindeer. But these are far from the only mammals with laryngeal diverticula located on the midline of the throat: small sac-like structures located on the ventral surface are also present in opossums (Didelphis), quolls (Dasyurus), some phalangers (Trichosurus and Phalanger), swamp wallabies (Wallabia), hedgehogs (Erinaceus), squirrels (Sciurus), marmots (Marmota), water voles (Arvicola), tapirs (Tapirus), horses (Equus), boar (Sus), eland (Tragelaphus), saiga (Saiga), takin (Budorcas), some bears (Ursus), wolves (Canis lupus), southern sea lions (Otaria) and various others (see Frey et al. (2007) for a complete list........ In some taxa, these structures are associated with enlarged hyoid bullae ....., but in others they are not. |
The larynx sits between the epiglottis and the cricoid cartiliage, and it hangs from the hyoid bone. It includes the epiglottic, thyroid, cricoid, arytenoid, corniculate, and cuneiform cartilages. In big cats, koalas, deer, some bats, and humans, the larynx is set unusually low within the throat compared to the normal mammalian condition. In newborn humans, the larynx is initially at the level of the C2–C3 vertebrae, but as the child grows it descends to its adult position near the top of the neck at the level of the C3–C6 vertebrae.
If you go to the image of the dissected head of the Mongolian gazelle at http://scienceblogs.com/tetrapo....tal-sac , you can see the larynx at the top of the trachea, in a Mongolian gazelle: it's the stuff between the back of the tongue and the top of the trachea is the larynx. It is similarly at the top of the trachea in giraffes, albeit a tiny bit deeper in the throat than in some animals (about half a skull-length's down, but still proportionally well above where it sits in people). You can just make it out in http://www.animalinsideout.com/downloa....916.jpg and http://cbsdallas.files.wordpress.com/2013.......y-2.jpg . The full length of the throat and the detour of the recurrent laryngeal nerve past the base of the throat do not seem relevant.
We guessed that earlier from thinking about sound production in elephants and alligators, but you didn't even get that far in your thinking.
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