Water Heater humming

Factual Questions
1

My Hot Water heater in the garage hums with a metallic ring when hot water is being used in the house. Usually it does it for a minute or two when hot water is first turned on, then the humming goes away. Is this a possible air bubble and draining the hot water heater could resolve it?

Thanks.

2

It might be debris on the bottom. When was the last time you drained it?

3

Why is your hot water heater humming?

It doesn’t know the words.

(I’m sorry. Someone had to say it.)