conversational sounding board

Hi,

I came across a sentence that is a bit unclear to me and would really appreciate your suggestions. It's from S.Kinsella's Confessions of a Shopaholic. Becky is visiting her parents and they've exchanged all the news, so now they're "grinding to a bit of a halt. We need the telly on, if only as a conversational sounding board." I looked up "sounding board" in a dictionary, but I would like some further explanation. Does it mean that there may be something on TV that would give them something to talk about?
Please help.

I didn't find the right solution from the Internet.

References:
forum.wordreference.com/threads/conversational-sounding-board.1160998/
Digital Campaign examples


Thanks