When your mesh's "read delay" is set to a value higher than 0, the timing-related options will appear in STM's inspector. So a boolean option for remember read position and ignore time scale will appear. (If you don't want the mesh to actually read-out, despite following these options, set the read mode to "all at once" and the animation to "Appear")
Also, what do you mean by "music"...? The text reading sound made by STM, or your game's background music...?