The gadget produces a cancelling signal, an opposite sound to knock out the sound of the drill.

这个装置会产生一个抵消信号，一种相反的声音来抵消钻头的声音。

So, we listen to the sound of the drill, we produce a cancelling signal which is really effectively an opposite sound – and then we just knock it out with the filtering system.

所以，识别了钻头的声音，再产生一个抵消信号，实际上是一个相反的声音，然后我们可以用过滤系统把它去掉。