Why do my chicks try to chirp louder than my vacuum cleaner?

[CozyDia]

Silly question I know, but I'm curious if there's any reasoning behind it. Why do my chicks try to chirp louder than my vacuum cleaner? When I turn it off their back to their quiet peeping, but as soon as I turn the vacuum back on they try to chirp as loud as the vacuum.

 

[BlueBaby]

The noise from the vacuum cleaner is probably scaring them.

 

[FunClucks]

Maybe they're scared? Are they making their scared peep or their "feed me" peep? Their scared peep can be very loud because they're calling their momma over to help them I think.