Iyar Doo-Wop Revival

My wife asked our Rav and received the answer that acapella music is OK during sefirah, so Shmais Radio has been playing constantly in our house. This is actually the first time since I have been married that any music has been playing in the house during Iyar. Where did this seemingly endless supply of acapella Jewish music come from? I am once again reminded that I have not been keeping up with Jewish music. I guess it is inevitable that much of it would sound like 50's Doo-Wop, but it's funny that it is so rhythm-and-blues derived so much of the time. Update: Some of it seems to have percussion. Is this OK? Does anyone know hilchos acapella? Should I just keep my mouth shut?

Tags: music, Jewish music, sefirah, acapella