注意在位置19上的峰值如何表示按键之间延长的停顿，但是其余的输入按相对接近的关系分组。
Note how the spike at position 19 indicates an extended pause between keys, but the rest of the entries are grouped in relatively close proximity.
这样一来，我们就能破译出按键音与特定按键的对应关系。
Thus to decipher what tone frequency is associated with a particular key. Look at your phone again.
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