Answer:
A static observer hears a sound whose frequency is appreciably different from actual frequency because here the change in frequency of the sound due to doppler effect.
Step-by-step explanation:
Given that,
Frequency = f
We know that,
The sound source of frequency f moves with constant velocity through a medium that is at rest.
A static observer hears a sound whose frequency is significantly different from actual frequency due to doppler effect.
We know that,
The doppler effect is defined as

Where, f₀ = actual frequency
f = observe frequency
v = speed of sound
= speed of observer
= speed of source
Hence, A static observer hears a sound whose frequency is significantly different from actual frequency because here the change in frequency of the sound due to doppler effect.