Simultaneous sound on TV and Headphones?

Hello,

We have a Sony Bravia TV. The main TV sound cuts out when one inserts the Headphone jack into the TV. How can one set the system up so that sound plays simultaneously on both the headphones and the TV. For those of you who may wonder why one would want this - I am hard-of-hearing so like to wear the headphones. However, my family would like to hear the TV at the same time. Thanks for your help.