名词
中文翻译：大声喊叫器
同义词：
['loudspeaker', 'megaphone', 'megaphone speaker']
例句：
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1. The loud-hailer was used to amplify the sound of the announcement.
扩音器被用来放大公告的声音。
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2. The loud-hailer was used to broadcast important news during the event.
在活动中，扩音器被用来广播重要新闻。
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3. The loud-hailer was used to create a loud and clear audio signal for the audience.
扩音器被用来为观众创造一个响亮清晰的音频信号。