The cones are crude acoustic loudspeakers devised by the dogs' awful owners to make their barks sound even louder. They are the dog-owners' equivalent of those loud rasping exhausts that 18-year-olds have fitted on their Peugeot 106s to go with their multispeaker bass-only sound systems which only work with the windows wound down. Big dog, big cone, big bass, small willy sort of thing.