In May Juche 101 (2012) the respected Comrade Kim Jong Un inspected the Kangsong Health Complex which was nicely built at a factory.

He went round a gymnastic room and suddenly looked for a basketball. Striking it down several times on the floor, he asked officials whether or not they could hear any sound around.

They did not see the reason for a moment, but after the moment they realized that he intended to examine soundproofing in the room. 

He felt satisfactory saying that it was excellent. 

They were quite moved to see the respected Comrade Kim Jong Un who was very much careful to get workers free from even slightest inconveniences.