the continuous music will make your contents and page very heavy…
Yes but if the visitor has to click a link to download and play the music then it doesn’t matter because only those who want to hear the music have that overhead.
you can use a frame and insert play button and load music url within this frame and the other frame will be content.
Just use an i-frame. It’s easy and will work. If you really want to force music on your viewers, do it! Obviously if it’s a commercial “customer is king” type website, then it’s a bad idea, but if it’s your personal website, make them listen to whatever you want, and remove the volume control! It’s your house 
Why are you guys suggesting an iframe instead of just loading the pages via ajax?
I think this way is good.
Why? To me landing on a site that automatically plays music is rude, and if I don’t need to be there I’m gone immediately. Otherwise I hit the mute button if I must do business!
Please reconsider having music play automatically! It’s like walking into someone’s house without having the courtesy to knock!
Chris