Why does the rice cooker beep when dinner's ready but I only hear it when I'm in the shower?

I set the rice cooker at 5:30 so dinner would be perfect by 6:00.

It beeped right on time.

Punchline

I was upstairs with shampoo in my hair and a towel rack between me and a hot meal. The rice cooker has impeccable timing — just not my timing.