问
（1）But every night he heard the noise upstairs.
(2) Sound travels slower than light.
(3) The idea that computers can recognize human voices surprises many people.
sound, noise 和 voice 都作“声音”解, 它们有没有什么区别呢?
答
在这三个词中，sound 的含义最广泛：凡是能听得见的声音都可以叫 sound，包括人声、鸟声、机器声等。这种声音可能悦耳，也可能是噪声。
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We heard a strange sound. 我们听到一种奇怪的声音。
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the sound of the wind, sea, a car, voices, breaking glasses 风、大海、汽车、人们说话、打碎玻璃的声音
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I heard the sound of a baby crying. 我听见有小孩儿哭的声音。