# TPR complete test3 #34 C/P section

#### akimhaneul

2+ Year Member
I am not quite understanding why the answer can include interference. Doesn't interference mean that two different waves combine with each other?

When the passage says "insect’s beating wings introduce oscillating frequency and amplitude shifts into the returning echo", does this mean that the insect's beating wings are creating a new wave in addition to the one emitted by the bat? And these two waves combine together during the doppler shift when going back to the bat?

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#### Mr. otcoD

I would have thought interference would be a part of it because think of it like this: in the passage it talks about how flies echolocate to prey (so not other flies) or dense objects. So the waves are going to be reflected back once it strikes the object (like an ultrasound)
But the question is talking about how a fly is intercepting ANOTHER fly, despite the dense background of vegatation. The other fly is therefore undergoing echolocation to get through the dense area. Hence the waves are going to be interfering with each other in that sense.

OP
A

#### akimhaneul

2+ Year Member
I would have thought interference would be a part of it because think of it like this: in the passage it talks about how flies echolocate to prey (so not other flies) or dense objects. So the waves are going to be reflected back once it strikes the object (like an ultrasound)
But the question is talking about how a fly is intercepting ANOTHER fly, despite the dense background of vegatation. The other fly is therefore undergoing echolocation to get through the dense area. Hence the waves are going to be interfering with each other in that sense.

The passage is talking about a bat and an insect...

#### laczlacylaci

2+ Year Member
Lol this might be a bad reference. If you've watched finding Dory, you know they talk about echolocation and they give a visual on how echolocation works.

The animal (ie. Bat) sends out a signal (wave forward) to an area. If there is a object (ie. The fly) then the signal ( wave back to the bat) will go back to the bat. The wave back to the bat (after it hits the fly) will interfere with the wave the bat originally sent out. This creates interference.

Let me know if that is still confusing. Try drawing a graph, maybe that'll help.