# Why does an ambulance have a higher pitched sound as it travels towards you use the Doppler effect to explain?

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## Why does an ambulance sounds high pitched on approach?

When the ambulance is approaching you the siren has a higher pitch than when it is moving away. The pitch of a sound wave tells us how often the waves encounter the listener. As the source of the sound waves comes closer, the waves bunch up close together. When it is moving away, the waves are stretched out.

## Why do you hear an increase in the pitch of an ambulance siren as it approaches you but then a decrease in that pitch when it moves away?

So why do we hear a change in pitch for passing sirens? The pitch we hear depends on the frequency of the sound wave. A high frequency corresponds to a high pitch. So while the siren produces waves of constant frequency, as it approaches us the observed frequency increases and our ear hears a higher pitch.

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## Why does the frequency of a siren get higher as an ambulance using that siren gets closer?

As the ambulance moves closer to you, the air molecules get compressed together. The wavelength of the sound (these pressure waves) decreases, and the frequency increases. That results in a higher sound pitch.

## Why does a siren on an ambulance sound different as it approaches you aks 9e?

As the ambulance approaches you, the distance between the source of the waves and the observer decreases. Consequently, the siren sounds more shrill as the pitch of the wailing siren ‘sounds’ higher than its original value, as sound waves reach you ‘more frequently’.

## What is the pitch of ambulance?

When an ambulance approaches you, you record the pitch of its siren at 3166 Hz. When it moves away, the pitch is 2850 Hz.

## What effect causes a siren to change in pitch as it passes by?

The Doppler Effect causes a siren to change pitch as it goes by you.

## What happens to the pitch of a sound if its frequency increases?

When you increase the frequency of a sound wave, the sound waves get compressed and we hear the sound at a faster rate. The pitch of the sound increases.

## Why does the siren get lower pitched when the ambulance moves away from you?

A: The siren will suddenly get lower in pitch because the sound waves will be much more spread out and have a lower frequency.

## What increases as sound waves increase in frequency?

If the frequency of a sound wave increases, the wavelength of the wave decreases. You hear the pitch of the sound from an ambulance siren get lower, then get higher.

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