Question

What is the quality of the sound of a fire truck’s siren when it moves toward a stationary hearer?

Answer 1

What is the quality of the sound of a fire truck’s siren when it moves toward a stationary hearer?
Its High Pitched

What is the quality of the sound of a fire truck’s siren when it moves away from a stationary hearer?Its Low Pitched

Answer 2

The pitch increases.

Step-by-step explanation:

According to the Doppler effect, the apparent frequency of the waves is different when there is relative motion between the source and the observer. When the source and observer approach, the apparent frequency (pitch) increases whereas it decreases when they recede away.

Thus, when a fire truck moves towards a stationary hearer, the pitch of the siren appears to increase.