For some people, they may not need earplugs, especially those who are used to sounds such as factory machines or others.
For the record: nobody "gets used to" loud noise. Hearing damage collects over the years, and every exposure to loud sound adds up. It might take years before you realize it's too late.If the sound produced by the letter knocker is above 85dB in one beat,
it will interfere with hearing, and usually when exposed to noise for too long the ears will ring.
