KELLY MCEVERS, HOST: Yesterday on the show, we played a couple of sounds for you.</s>KELLY MCEVERS, HOST: One is the sound of hot water being poured into a glass, the other is of cold water being poured into an identical glass. We asked you to go on our website and tell us whether you could tell which was which. And a lot of you took us up on it - like 30,000 of you. And 80 percent of you guessed that this...</s>KELLY MCEVERS, HOST: ...Was cold water. You were right. This...</s>KELLY MCEVERS, HOST: ...Of course is hot water. Ninety-one percent of you got that one right. Our poll was based on a larger experiment that found nearly all people surveyed could tell the difference between hot and cold by sound alone. The firm behind the experiment hopes to use the findings to make better sounds for ads, for example, to make a cold beer sound colder by accentuating the high-pitched ping at the end of the pour. Cold water is more viscous, or sticky, than hot water. That's what makes that high pitched ringing, and it's what tells your brain - this glass of water is cold - before you even take a sip.
NPR conducted an online poll asking listeners if they could hear the difference between cold and hot water simply by listening to the sound of the water being poured. Most listeners were spot-on.