Dog-eared

Watching the news this morning, they had an ad on for the local production of "Phantom of the Opera". My dog was sitting next to me, waiting for crusts from above while I ate breakfast, and I wondered what he hears when we hear music. Does it make any sense at all to a dog, or is it just a cacophony of noise? When we sing, does he wonder what the heck that sound is coming out our mouths? Or does he simply just not care?

I know they pick up sounds they recognize - there's one ad where a lady whistles for her dog, much the same way we do for ours, and they usually jump up to see who is calling them. But dog-food ads, filled with barking dogs, they usually ignore (perhaps the message those dogs are barking is irrelevant). Only one other time has one of the dogs noticed a dog on the TV - barking or whining, not sure which - and pricked up his ears.

I know dogs only see certain colours, but I wonder what they hear...