NCIS season 4 has 24 episode guides and currently identifies 38 soundtrack songs.
NCIS season 4 episodes
Episode 1
Sep 19, 2006
3 songs
Episode 2
Sep 26, 2006
4 songs
Episode 3
Oct 03, 2006
1 song
Episode 4
Oct 10, 2006
1 song
Episode 5
Oct 17, 2006
--
Episode 6
Oct 31, 2006
2 songs
Episode 7
Nov 07, 2006
2 songs
Episode 8
Nov 14, 2006
4 songs
Episode 9
Nov 21, 2006
3 songs
Episode 10
Nov 28, 2006
1 song
Episode 11
Dec 12, 2006
--
Episode 12
Jan 16, 2007
1 song
Episode 13
Jan 23, 2007
2 songs
Episode 14
Feb 06, 2007
--
Episode 15
Feb 13, 2007
1 song
Episode 16
Feb 20, 2007
--
Episode 17
Feb 27, 2007
--
Episode 18
Mar 20, 2007
5 songs
Episode 19
Apr 03, 2007
1 song
Episode 20
Apr 10, 2007
1 song
Episode 21
Apr 24, 2007
2 songs
Episode 22
May 01, 2007
--
Episode 23
May 08, 2007
--
Episode 24
May 22, 2007
4 songs