Background music help

I’m trying to make it when i collect pages in my slender game. The music changes. I have 3 different self made audio clips for the music. But when i collect the pages the music plays horribly stacked. Heres the part of my code:

               if(pages == 6){
			Application.LoadLevel(3);
		
      }

    else if (!audio.isPlaying && pages >= 5) {
      audio.clip = Page5_6;
      audio.Play ();
     }
     else if (!audio.isPlaying && pages >= 3) {
      audio.clip = Page3_5;
      audio.Play();
     }
     else if (audio.isPlaying && pages >= 1) {
	   audio.clip = Page5_6;
       audio.Play();
     }

you are playing 5_6 twice
this line is missing the !

else if (audio.isPlaying && pages >= 1)

replace with

else if (!audio.isPlaying && pages >= 1)

You need to replace the line:

else if (audio.isPlaying && pages >= 1)

With:

else if (!audio.isPlaying && pages >= 1)