空气声air-borne sound

A、照明 Lighting

B、装饰 Decoration

C、隔声 Sound Insulation

D、供热 Heating

A.支持索尼Hi-Res认证

B.拥有MI Sound大音腔

C.保留3.5mm耳机接口

D.支持杜比全景声

A．BR bass专利心里声学低音科技

B．Original Sound原音复刻引擎

C．BR Surround环绕声场

D．屏幕声场，声随影动

mmercial airliners travel faster than sound is the difficult problem of sonic boom (声震) , the explosive sound generated when an object moves through the air at supersonic speed(超音速).

A sound is a pressure disturbance: a sonic boom, like other explosive sounds, is the result of an abrupt change in pressure. An airplane in subsonic flight produces weak changed in pressure, but because these disturbances travel at the speed of sound, they move faster than the airplane and stay in front of it. In effect, these disturbances warn the air to get out of the way, and the an does just jet, however, gets ahead of its own pressure disturbances. Consequently a wave of suddenly com pressed air--a shock wave--builds up and is thrown off like the wave ;hat spreads from the bow of a speedboat.

Can sonic booms be eliminated？ The answer is a categorical negative--they are an innerent(内在的) part of supersonic flight--but the sonic boom probably can be reduced; government and private research is now under way to improve understanding of the sonic boom. If and when the booms can be reduced to tolerable levels, commercial supersonic transports can come rata service.

Before commercial airliners travel faster than sound, problems must 0e solved regarding ______.

A．design

B．Construction

C．operation

D．all of the above

litary radar system from Israel even though Israeli officials have confirmed they are supplying the technology, Reports of the 250 million-dollar sale appeared in the New York Times newspaper last week.

According to the news, the Chinese spokesman ______.

A．rejects the report that China is importing advanced military equipment from Israel

B．criticizes an unnamed country for spreading the rumor

C．denounces the New York Times report as irresponsible

D．admits there is military cooperation between China and Israel

A.传声器、放大器和耳机全部镶嵌在机器内部，患者可以操纵的外部设置包括M-T-O开关、音量旋钮等都在机器的背面

B.放大后的声音经耳钩(Earhook)通过一根导声管传入耳模的导声孔(Sound Bore)中

C.适于各种听力损失的患者，传声器的开口向前，利于面对面交谈

D.对于一些戴眼镜的患者(尤其是眼镜腿较粗的)会有不便

E.对于经常出汗的患者，助听器也易受潮，从而加速元器件的老化，导致损坏

Music

Music is one of the most beautiful forms of artistic expressions ever invented. In movies and plays, music has an added function: it not only moves people but also can shock people.

Our eardrums can withstand sound within 20 to 80 decibels (分贝 ) . Once sound exceeds this limit, even beautiful music will become car-splitting noise and harm health. A strong blast (响声 ) of high sound can twist and break a solid iron sheet. High sound of 150 decibels can kill a healthy rat.

In movies, sometimes the hero can produce a sound that ordinary people can&39;t hear and only those who have the same ability can feel. In nature, there is actually sound that is beyond our hearing. In physics, the sound that exceeds 20,000 hz is called ultrasonic (超音波的). Dolphins, whales and bats can make such high-frequency sound. It does no harm to health.

Sound less than 20 hz is called infrasonic (次声 ) waves. When we move, the air will vibrate.

The vibration of air can produce infrasonic waves. As the frequency of infrasonic waves is close to that of people&39;s internal organs, infrasonic wave may cause resonance (共振) in human bodies. As a result, people&39;s vision may weaken and internal organs may rupture (断裂). However, whether an infrasonic wave can be used as a weapon depends on its intensity. If its intensity is very low, it won&39;t damage internal organs or a person&39;s health. If the intensity of infrasonic wave exceeds 160 decibels, it is extremely harmful. When wind blows at a force of 3 or 4 over the sea, it will produce infrasonic waves of several decibels. Only typhoons can produce infrasonic waves of over 100 decibels. At present, scientists can only produce infrasonic weapons in the lab with the help of advanced scientific tools and powerful electric power.

What could be the best title of the passage？ 查看材料

A.The power of music

B.The harms of noises

C.The magic of sound

D.The discovery of infrasonic waves

A.0

B.1

C.10

D.0.2