Why won't the music stop?

So I go into queue to search for a ranked game but during the champion selection page, I noticed that the music that runs during the lobby search was still going on in the background. It wouldn't stop, even after we went into game. Please this happened to me once before on a separate account in a normal game too. I left the game and closed the client which fixed the problem, but by the time I came back, the game was lost, my team was angry and I was reported. It was so annoying, the Summoner's Rift music and the lobby select music going on at the same time...PLEASE FIX.