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August 15[edit]

Artificial improvement of acoustic transmission[edit]

Is it theoretically possible to maximally improve the acoustic transmission and lower the acoustic impedance within some enclosed space, e.g. by warming the air and pumping more air within safe pressure limits for human body, with the aim of better hearing quiet and distant sounds? Excluding existing examples of acoustically designed music venues and opera houses. 212.180.235.46 (talk) 10:19, 15 August 2022 (UTC)[reply]

There was an accident where oil rig divers were in a slow depressurization chamber (to prevent the bends) and at least 9-10 bar made their bodies sort of explode when both sides of an airlock were open simultaneously. Sagittarian Milky Way (talk) 13:08, 15 August 2022 (UTC)[reply]

Have you any more data on that? Normally the doors are designed such that they can only be opened where the pressure is equal, typically by only opening towards the high pressure side. Martin of Sheffield (talk) 13:11, 15 August 2022 (UTC)[reply]

Byford Dolphin. Actually it was 9 atmospheres above vacuum, only ~8.005 atmospheres above outside pressure. Sagittarian Milky Way (talk) 13:23, 15 August 2022 (UTC)[reply]

Thanks. It makes horrific reading, the only saving grace is that death must have been instantaneous and they would have known nothing about it. I do note though that the design was from 1975 and the Norwegians were already tightening up on it. Brrr. Martin of Sheffield (talk) 13:43, 15 August 2022 (UTC)[reply]

To truly maximize pressure and the speed of sound you'd need to fill it with pure pressurized hydrogen and breathe 0.something precent oxygen the rest hydrogen through a mask at similar pressure to get as close to the world record of c. 70.1 atmospheres as you dare which would cause health problems and make some instruments octaves higher (but not speakers playing a recording). It would also be uncomfortably hot which would pollute the hydrogen with a possibly small amount of dried sweat. I suppose you could paint a thin coat of something waterproof and airtight on the ear canal (not the eardrum) and wear a backless waterproof airtight suit with a seal at each ear opening and instead of a back a silhouette-sized tunnel connected to the most silent cooling system possible providing air conditioning from out of earshot. And wear old-fashioned gramophone-looking ear cones if that's not cheating. Sagittarian Milky Way (talk) 21:15, 15 August 2022 (UTC)[reply]

One issue with any optimization you're suggesting in a real-human-world environment (like a concert) is that I think anisotropies in the air and noise propagation will cause far more signal loss than any gains reducing impedance might bring. Obviously your sound is great in the ocean (once you filter out the insane amount of noise), but that's an enormous change in impedance, and I'm not sure, but it might be that you'd expect the local anisotropy (that is, over a fixed volume) of something like air on Earth at sea level in good conditions to be greater (in manners that would most affect acoustic signal) than that of water or the ocean in some other reasonable real-world circumstance (and the reason I think this is reasonable is that water will generally have uniform density throughout these volumes whereas air in these conditions need not). SamuelRiv (talk) 23:54, 15 August 2022 (UTC)[reply]

Fun almost irrelevant fact. Tires have a ring mode in which a resonant wave forms around the circumference.It can be a bit hard to identify it (to the cloth eared, it is clear as a bell to me), so we fill the tire with CO2 and see which resonances move in frequency. Greglocock (talk) 00:00, 16 August 2022 (UTC)[reply]

Besides the telegraph key...[edit]

... (or maybe it isn't even functioning here as a telegraph key), can anyone explain what else is going on with this board, recently seen in an antique shop in Oregon? - Jmabel | Talk 18:47, 15 August 2022 (UTC)[reply]

Some sort of Wheatstone bridge perhaps. catslash (talk) 20:51, 15 August 2022 (UTC)[reply]

A similar one from a New Mexico University Physics lab was sold on Ebay: https://www.worthpoint.com/worthopedia/chicago-apparatus-company-wheatstone-1855290011 Modocc (talk) 21:03, 15 August 2022 (UTC)[reply]

Very similar indeed - and it confirms that there should be metal pegs.catslash (talk) 21:12, 15 August 2022 (UTC)[reply]

Also that the banana connector-cum-binding post terminals are not original.catslash (talk) 21:37, 15 August 2022 (UTC)[reply]

It's clear that the wound impedances are designed to be shunted by the insertion of metal pegs - so that in the absence of the pegs, both upper branches are each set to 111ᾨ.

Probably the screw terminals form a pair, likewise the terminals labelled x-x, the two top-centre terminals and the two bottom right terminals. catslash (talk) 21:05, 15 August 2022 (UTC)[reply]

It's a demonstration Wheatstone Bridge, new form. Catalogue number 1073E "Easier for the student to understand". Cost $13.50 new. DuncanHill (talk) 21:26, 15 August 2022 (UTC)[reply]

Thank you all! - Jmabel | Talk 22:36, 19 August 2022 (UTC)[reply]