I found two sounds related bugs. It can be best explained if I say how to reproduce them.

Note: For both of the bugs, I pressed Esc when I resumed the game. I don't know if clicking Resume Game will give the same results.

Steps to Reproduce Bug #1:
1. Make sure the music volume slider is at 100%, and wait for the random music to start playing.
2. Wait for the music to almost be done (Or at any point where the music's still playing), pause the game then resume it.
3. The music will have restarted, instead of resumed. Repeat step 2 until a different song starts playing, at which point two songs will be playing at once.

Steps to Reproduce Bug #2:
1. Grab a jukebox and a music disk (any disk) from either the creative inventory, or by crafting them, then place the jukebox anywhere.
2. Making sure the noteblock / jukebox volume is at 100%, insert the music disk into the jukebox.
3. Pause the game and go to the music & sounds options. Drag the noteblock / jukebox to 0%, but don't let go of the mouse button afterwards.
4. While keeping the mouse button held, press Esc. If done correctly, the music from the jukebox can still be heard even though the slider was set to 0%.

An additional note about bug #2, every time you pause then resume the game, the music from the jukebox will have restarted.