回复：回复：不是说话的声音，而是莫名其妙，肆无忌惮的撞击碰撞声，非常响，当是由于那个人的习性所致。

Thank you for providing the necessary informations and helping to envision the possible scenarios. Especially with B), I shall need to think of how to present the situation to the police officer when he arrives.

Thanks again.