"I'm glad that you understand that," Robin's mother replied with pride.
"As the
helicopter flies through the air, the sound it makes moves in waves through
the air.
Most of the sound waves caused by the helicopter move out in front of the
helicopter. We fly the airplane in front of the helicopter so the microphones
record
the loudest sound made by the helicopter," Jackie finished her explanation.
"That explains why helicopters are even louder when they
are landing," Robin said as
she put her hands over her ears. They laughed together as they approached the
computer lab.
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