You can demonstrate for yourself this fluctuation of attention.

你可以自己证明这种注意力的波动。

You can demonstrate for yourself this fluctuation of attention. In a quiet room, place a watch so that it can just scarcely be heard.

您可以亲自演示这种注意力的波动。在安静的房间里，将手表放置在几乎听不到声音的地方。