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. Is it true that an ordinary musical instrument can be so
powerful? Our eardrums can withstand sound within 20 to 80
decibels. Once sound exceeds this limit, even beautiful music will become
ear-splitting noise and harm health. A strong blast of high sound can twist and
break a solid iron sheet. {{U}} {{U}} 1 {{/U}} {{/U}}
The noise from a plane's engine is over 140 decibels. However, the sound
of a flute is at most a few decibels. {{U}} {{U}} 2 {{/U}}
{{/U}}It has been proven that people who have worked in an environment with a high
sound intensity for a long time suffer varying degrees of heart disease or
altered brain waves. In movies, sometimes the hero can produce
a sound that ordinary people can'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 20,000Hz is called ultrasonic. {{U}}
{{U}} 3 {{/U}} {{/U}}It does no harm to health.
Sound less than 20Hz is called infrasonic waves. When we move, the air will
vibrate. {{U}} {{U}} 4 {{/U}} {{/U}}As the frequency of
infrasonic waves is close to that of people's internal organs, infrasonic wave
may cause resonance in human bodies. As a result, people's vision may weaken and
internal organs may rupture. However, whether an infrasonic wave can be used as
a weapon depends on its intensity. If its intensity is very low, it won't damage
internal organs or a person's health. {{U}} {{U}} 5 {{/U}}
{{/U}}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. A．High sound of 150 decibels can kill a healthy
rat. B．The vibration of air can produce infrasonic
waves. C．We cannot play high pitched music with ordinary
musical instruments. D．If the intensity of infrasonic wave
exceeds 160 decibels, it is extremely harmful. E．Dolphins,
whales and bats can make such high-frequency sound.
F．Therefore, the sound of ordinary musical instruments cannot harm your
health.