Grand Central Terminal whispering gallery (Oyster Bar arches)

The tiled Guastavino arches in Grand Central Terminal's lower-level Oyster Bar are a well-known whispering-gallery acoustic phenomenon: a whisper spoken into one corner of an arch can be heard clearly at the opposite corner. The effect is commonly demonstrated by visitors and mentioned in guides to the terminal as an unusual architectural acoustics feature rather than a supernatural occurrence. The site has been written about in newspapers and architectural guides as a distinctive curiosity of Grand Central.