Answer:
The perceived frequency is higher than the actual emitted sound frequency. that means that the received sound waves are of shorter wavelength.
Step-by-step explanation:
When the source of a sound wave is moving toward the observer, the perceived frequency of the wave changes in relation to the observer producing a change in pitch. The effect is called Doppler effect in honor of the physicist who formulated the physical explanation.
In the case of the sound source approaching the observer, the perceived frequency is higher than that actually emitted by the sound source.