This mod from Soulburner disables all in-game music.
Readme File:
NoMusic - disable music in Call of Duty 4
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Version: 1.0
Author: Soulburner (liquid_man@o2.pl)
Description: Disables in-game music to make the game more realistic.
As you've probably noticed, there is no option to disable
music in the game menus.
Installation: Extract this archive to the Mods directory in you Call of
Duty 4 folder, for example c:Program Filescod4Mods.
Now, modify your shortcut's properties and add this in the
Target element: +set fs_game Mods/NoMusic,
for example:
c:program filescall of duty 4iw3sp.exe +set fs_game Mods/NoMusic
Check attached install.png screen for more.
You may distribute this modification freely as long as you keep this readme file.