My father installed a Nutone intercom system into our house when I was
growing up. The 'main' unit was in the kitchen and it had an AM-FM radio
as part of it. My father installed speakers in all of the bedrooms, the
basement, the patio on the side of the garage, as well as by the front
door on the porch. Not only could you pipe music to all of those areas,
you could 'talk' to people in those spots, or eavesdrop on them if you
were feeling wicked. And you could ask who was at the front door ringing
your doorbell without getting up. It was really high tech back in the
day. The unit is still in the house, my daughter and her family live
there now, but I don't know if it still works. I'll have to ask.