Answer:
168 Hz
Explanation:
The Doppler equation describes how sound frequency depends on relative velocities:
fr = fs (c + vr) / (c + vs),
where fr is the frequency heard by the receiver,
fs is the frequency emitted at the source,
c is the speed of sound,
vr is the velocity of the receiver,
and vs is the velocity of the source.
Note: vr is positive if the receiver is moving towards the source, negative if away.
Conversely, vs is positive if the receiver is moving away from the source, and negative if towards.
Given:
fs = 164 Hz
c = 343 m/s
vr = -15 m/s
vs = -23 m/s
fr = fs (c + vr) / (c + vs)
fr = 164 Hz (343 m/s − 15 m/s) / (343 m/s − 23 m/s)
fr = 168 Hz
