Question

what is the name of the perceived change in a sound waves frequency due to motion between the observer and the sound source?
diffraction
doppler effect
reflection
resonance

Explanation:

The Doppler effect is the perceived change in frequency of a wave (like a sound wave) due to relative motion between the observer and the source. Diffraction is about waves bending around obstacles. Reflection is when waves bounce off surfaces. Resonance is when a system vibrates at its natural frequency. So the correct answer is the Doppler effect.

Answer:

B. Doppler effect