Elliptical rooms focus whispered sound at the opposite focus
Evidence
By placing one person at each of the foci of an ellipse, whispering conversations may take place over many tens of meters. Figure 27.10 (right) shows why: all the ray paths from one focus of the ellipse converge on the other focus after one bounce. (An elliptical gallery will support both types of whispering gallery effects.) All the ray paths have the same length, so the sound arrives intact but, somewhat disconcertingly, from all directions at once—that is, all but the direct sound, which arrives earlier, without a reflection. (As explained in section 21.2, this early arrival is likely to lead to our correct impression that the speaker is at the other focus, even though the reflected sound may be many times louder than the earlier direct sound.) — Eric J. Heller, Why You Hear What You Hear- An…, 2517
Categorization
- XREF: Connects to the earlier account (section 21.2) of precedence/early-arrival effects governing sound localization — which focus the sound seems to come from. — connects to: Curved surfaces concentrate sound locally while draining power elsewhere in the room
- CANDY: Ellipse whispering galleries are a delightful party-trick physics fact — whispered secrets travel tens of meters between sofa foci.
- corroborated: 2 independent passages support this claim — Eric J. Heller, Why You Hear What You Hear- An…, 2517