Question

As police car with a blaring siren driver away from you while are on standing near intersection, the frequency of the siren is _____therefore, the pitch of the siren is _____.
A) lower, lower B) lower, higher C) higher, louder D) higher, lower E) higher, higher

Answer 1

Through the principle or law of Doppler effect, it can be deduced that when the object is approaching one that is stationary, its frequency is increasing. Frequency and pitch are two items which are in direct proportion. This means that a higher frequency sound corresponds to a higher pitch. 

Hence, the answer to this item is letter E. higher, higher.