Never heard ROS sound like that.
Right. Maybe somebody playing music on 27.175 for fun? Or as part of an "interval signal" of sorts to indicate that the channel is about to be used?
I remember seeing a video on YouTube made by a European CBer - he was hearing Arabic music and melodies on several frequencies on the "low channels" on 26 MHz, I believe 26.785 MHz, 26.795 MHz, 26.865 MHz or nearby frequencies, all in FM mode. He wasn't sure where they were coming from either. After the music there would be an OM speaking Arabic. Good signals too.