The correct statement that accurately describes the changes in sound waves associated with the Doppler Effect is:
**Sound waves experience a decrease in frequency when the source of the sound is moving away from the observer.**
This is because, as the sound source moves away from the observer, the sound waves are stretched, leading to a lower frequency (and thus a lower pitch) from the observer's perspective. Conversely, if the source moves towards the observer, the frequency experienced by the observer would increase.