You can turn off Sound and Music in the Settings Menu.
At the bottom of the screen, tap on the Settings "cog" icon. At the top of the screen, you can tap on Music and Sound to toggle them on or off.
If you're having other issues with your game audio, feel free to contact Support in-game, or send us a message at https://smurfsmagicmatch.zendesk.com/hc/en-us and our Support Team will assist.