Normally in vanilla Doom, sound effects decrease in volume with distance, with a cutoff at 1200 units. Sound effects originating at a distance of more than 1200 units from the player are not heard. This behavior is different on level 8. This affects level 8 when playing under any episode of Doom/Ultimate Doom as well as MAP08 of Doom II or Final Doom. When playing on level 8, sound effects are not cut off. As the boss levels in Doom 1 all occur on level 8, it is likely that this behavior was intended so that the player could always hear the boss monster from any distance.