科学家认为，公共广播系统、扩音器、自动门等利用超声波控制的设备日益增多，可能会导致“超声病”的流行。

Scientists say that a boom in public announcement systems, loudspeakers and automatic doors may be spawning an epidemic of ultrasonic sickness.

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公共广播系统是专为公共场所提供背景音乐、广播及消防报警的专业设备。

The public broadcast system specially provides the background music for the public place, it is also the specialized equipment which broadcast the fire alarm to the public.

youdao

公共广播系统是专为公共场所提供背景音乐、广播及消防报警的专业设备。

The public broadcast system specially provides the background music for the public place, it is also the specialized equipment which broadcast the fire alarm to the public.

youdao