Question

You hear a sound in the distance. Suddenly the sound gets deeper, decreasing in pitch. Which can you assume about the sound waves reaching your ears? A. The wavelengths of the new sound waves are longer. B. The amplitude of the new sound waves has increased. C. The sound waves have changed their speed so that they are now moving more quickly through the air.

Answer 1

Answer:

A. The wavelengths of the new sound waves are longer

Explanation:

This is the Doppler effect which can be best illustraded  for the case of a siren of an ambulance approaching us having a greater frequency and getting lower in frequency and deeper as the ambulance passes  us.

Since the wavelength is inversely proportional to the frequency it follows the wavelengths are longer when the frequency decreases lowering its pitch and getting deeper.