How Does The Doppler Effect Change Sound Frequency?

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Imagine a dog chasing you while barking. If the dog stays still, every woof reaches your ears at the same distance apart. But when the dog runs toward you, each new bark is sent from closer than the last one. This makes the sounds squish together, creating higher pitches.

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Sound travels in waves like ripples on a pond. When the source moves forward, it catches up to its own ripples. These compressed waves hit your ears faster, making them feel sharper or higher. If the dog runs away, the waves stretch out and become deeper.

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• A race car zooming past sounds like it drops in pitch suddenly.
• Ambulance sirens seem higher when they come toward you.
• The wind howling through a moving train feels different than when standing still.