A note has a fundamental tone- the pitch we hear- and a series of overtones that occur at higher frequencies.

每个单音都有一个基本调—我们听到的音调—以及一系列的高频调外音。

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The team then took a fundamental tone pitched below 5 kHz and digitally filtered it to leave just the overtones above 6 kHz.

研究小组接着选取一个音调低于5千赫兹的基本音，滤掉低于6千赫兹的所有声音。

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These are called "distortion products" and happen at multiples of the fundamental test tone.

这些称“畸变产品”并且发生在根本测试口气的倍数。

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While there appear to be some fundamental differences between the two sides, the left-wing rebels seem to have adopted a conciliatory tone.

BBC: Colombia peace talks 'in mambo rhythm', say Farc rebels