A siren makes a strange, pulsing sound because it’s sending out many different sound waves at once. When the siren is moving toward you, the sound gets louder and higher, like when a car zooms past you on the road. And when it moves away, the sound gets softer and lower. This is called the Doppler effect, and that’s why sirens make such an interesting noise!
Examples
- A fire truck siren sounds louder and higher-pitched when it’s approaching you.
- You hear a police car’s siren change pitch as it passes by.
- An ambulance siren seems to go from high to low as it drives away.
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See also
- How Does Sound Travel Through the Ocean?
- What Causes ‘Sound’ and Why Do We Hear It Differently in Different Places?
- What Causes the ‘Sound’ of a Bell and Why Do Some Bells Resonate Longer Than Others?
- What Causes the ‘Sound’ of a Bell Tower?
- What Causes the Sound of a Bell?
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