Wikipedia:Reference desk/Archives/Science/2018 January 31

= January 31 =

Speaking tubes
Why is the whistle of a speaking tube at the receiving end and not the transmitting end? Having it at the receiving end leads to the possibility of it not being replaced after a conversation, and thus leaving the chap at the other end not being able to give the chap at the other end a tinkle. DuncanHill (talk) 21:50, 31 January 2018 (UTC)
 * The article you linked says "...with whistles at either end" (whistle tubes). 2606:A000:4C0C:E200:855B:A505:748:9655 (talk) 23:36, 31 January 2018 (UTC)
 * The article I linked says "Later designs of the voicepipe inserted a removable cork-mounted whistle, which could be sounded by blowing into the tube from the other end. On naval vessels, this created a distinctive sound associated with urgent intra-ship communication on old warships. The sound of the whistle would summon the listener, who would remove the whistle and answer the call." DuncanHill (talk) 00:09, 1 February 2018 (UTC)
 * You can't hear a speaking tube unless you put your ear to it. You can hear one at the whistle end, if it's blown. Andy Dingley (talk) 00:18, 1 February 2018 (UTC)
 * Even a loud whistle from the other end? Does anyone have a speaking tube I can experiment on? DuncanHill (talk) 00:29, 1 February 2018 (UTC)
 * In a quiet environment, you would hear a loud whistle from the other end, especially if the receiving end gradually increases in size like a horn speaker to allow the sound out into the space, but a local whistle will be much easier to hear. Try it! A length of garden hose might suffice for the experiment.  Dbfirs  08:34, 1 February 2018 (UTC)


 * The single tube is a two way system, so can't simultaneously taper both ways! For a whistle to be blown at the caller's end (which might be either actual end), the tube would initially have to be open at both ends; the caller would then have to insert a whistle, then blow it, then remove it and listen for a reply, then repeat the whole process if the callee didn't hear the first whistle. The caller would also have to remember to re-stow the whistle at some location close to the tube, from where it might be dislodged and lost.
 * If the whistle is to sound at the callee's end, each end is by default plugged by its whistle; the caller removes the whistle at his end, blows, and listens, the callee removes his end's whistle and replies, and at the end of the conversation both whistles are replaced in their ends of the tube. This process is simpler and makes the misplacement of either whistle less likely, as the default has the whistle stowed on/in the tube. As Andy Dingley and Dbfirs have already indicated, this also means that the whistle will be considerably easier for the callee to hear, as a naval ship in operation is generally far from being a silent environment.
 * A further advantage is that keeping both ends whistle-plugged by default lessens the likelihood of getting a mouthful of spider! {The poster formerly known as 87.81.230.195} 2.221.83.136 (talk) 10:46, 1 February 2018 (UTC)


 * A single narrow tube can have an open tapered horn at each end (see Impedance matching), and this would work 2-way in a quiet environment, but otherwise I agree 100% with what you write above.  Db<i style="color: #4fc;">f</i><i style="color: #6f6;">i</i><i style="color: #4e4;">r</i><i style="color: #4a4">s</i>  11:12, 1 February 2018 (UTC)
 * Royal Navy whistles were retained on a bit of chain like this so that they didn't get lost. Alansplodge (talk) 17:55, 1 February 2018 (UTC)
 * Thank you all. I'd still like to test this properly, if anyone has a spare destroyer they could lend me One can avoid spiders by remembering not to suck. DuncanHill (talk) 18:40, 2 February 2018 (UTC)