Why is the background music louder than the talking?

Why is the background music louder than the talking? In a system designed for surround sound, the absence or incorrect integration of a central sound bar can make the dialogue much harder to hear, as can listening to it without the system type the mix was designed for.

In a system designed for surround sound, the absence or incorrect integration of a central sound bar can make the dialogue much harder to hear, as can listening to it without the system type the mix was designed for.