Final answer:
Widely spaced waves indicate a longer wavelength, resulting in a lower frequency and therefore a lower perceived pitch. This is the opposite effect of the Doppler effect, where sound waves compress towards a moving observer, creating a higher pitch.
Step-by-step explanation:
When waves are widely spaced, it means the wavelength is increased. A longer wavelength in a sound wave corresponds to a lower frequency, since the speed of sound is typically constant in a given medium. Consequently, the observer perceives a lower pitch because pitch is directly related to the frequency of the sound wave. This effect is opposite to the Doppler effect, where the observed frequency increases (and thus the pitch) if the source of the sound is moving towards the observer, and decreases if the source is moving away. The Doppler effect is a result of the compression of sound waves in the direction of the motion of the source and the elongation of the wavelengths in the opposite direction.