Who's Deaf?

There is a husband and a wife and the husband is worried because he thinks his wife is going deaf.. So the husband goes to the doctor and says "My wife is losing her hearing what do I do?"

"Do a test." says the doctor. "Ask her a question from 40ft away, 20ft, 10ft and 5 ft away. See when she starts to hear you."

So he went home and asked his wife from 40ft away when dinner will be ready.

No response.

20ft no response.

10ft no response.

At 5 ft his wife replies "For the 4th time dinner will be ready in 10 minutes!"