C
A fly with an extremely unusual ability to hear is the model for what may be the future of new and improved hearing aids. The insect behaves like a parasite—an organism that lives on or in another organism called a host. This exceptional fly places larvae—young flies onto a cricket (蟋蟀) host. The larvae dig into the cricket and eat the insect from the inside out.
The tiny yellow fly lives in Central America and the Southern United States. It finds its host by listening out for the cricket’s high chirping voice. The fly can easily find a cricket from as far away as 91 meters.
Neal Hall is a sound engineer who worked on the new hearing aid model. According to him, the fly’s behavior is very strange. Mr. Hall and his team at the University of Texas made a copy of the fly’s hearing structure. “They discovered that the fly has a clever mechanism and instead of using two independent ears like a human does, the fly’s ears are actually coupled,” said Hall.
The fly’s ears are two millimeters apart. That distance is so small that sound reaches one ear just four millionths of a second before arriving at the other. Experts held that it should be impossible for the fly to identify where a sound is coming from. In fact, however, inside this fly’s each ear is a 1.5-millimeter-long structure similar to a see-saw — a piece of children’s playing equipment. Like the see-saw, the fly’s ear structure goes up and down from a central point. Pressure waves against the structure increase the time it takes for sound to travel and permit the fly to find its host.
Mr. Hall and his team used the chemical element silicon to copy the fly’s ear structure. They also used the special electric materials that enabled them to measure its movements at the same time. Hall said that the hearing aid device could be used in two ways. One way would be to help the military on the battlefield, where sensors could find where shots are coming from. The other would be to remove unwanted noise from a person’s surroundings.
“It is a feature that is incredibly useful for hearing aids, for example, here and now, if you turn up the gain of a hearing aid or turn the volume up to hear someone across from you, it also amplifies (放大) everything else in the room,” said Hall.
Hall said that the next test in marketing the hearing aid device was to make it usable. He said the device must be handled carefully because it is so small. He noted that the fly does not have this concern.
Neal Hall is trying to     .

A．model his new hearing aid on a kind of fly

B．help crickets to prevent themselves from parasites

C．kill the insects in a host with a new machine

D．make powerful killers with the help of a kind of fly

What is the key message of Paragraph 4?

A．The distance between the fly’s two ears.

B．The special structure of the fly’s ears.

C．The comparison between the fly’s ears and see-saws.

D．Pressure waves against the structure of the fly’s ears.

With the help of the new hearing aid, people would be able to     .

A．find out where the flies come from

B．fall asleep when they want to

C．protect the peaceful environment better

D．choose to hear what they want to

What is the author’s attitude towards Neal Hall and his team mentioned in the passage?

A．Objective.	B．Tolerant.
C．Doubtful.	D．Pessimistic.

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