Wednesday, May 21, 2014

 

Why does a police, ambulance siren go up and down?

Q: Tradition?
A: A little, but old sirens were normally bells which sound a lot different.  There's a more scientific answer.

Q: Is it because you can hear it better?
A: Yes, but why.

Q: Because it's loud?
A: No, it could be loud but make a different sound.  Sirens are almost always going up and down in pitch.

A: The issue is with older people, or people with partial hearing loss.
A: Often you lose hearing at certain frequencies first.
A: By varying the frequencies you have a better chance of finding a frequency that even a person with partial hearing loss can hear.

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