Can you hear where that ambulance is coming from?

Because humans have ears on each side of their head, they are able to localize most sounds. The direction of high-frequency sounds is pinpointed based on their volume level in each ear, and low frequency sounds based on their arrival time in each ear.

But Guy Moore, an assistant professor of physics at McGill University in Montreal, said human ears do not do a good job finding the source of sounds around 1,000 hertz using either method, so that a noise in that range seems just as likely to be coming from the television to the right as a purse sitting to the left.

"That's also why it's so hard to tell where an ambulance siren is coming from in traffic," Mr. Moore said.

I may be time for some people to think about the frequency our sirens use. After all it might make a big difference if you could tell, where the sound is coming from!