Sound effects behave differently on level 8

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 1 as well as MAP08 of Doom 2 and 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 possible that this behavior was intended so that the player could always hear the boss monster from any distance. As an additional effect, if the sfx volume is decreased to zero, sound effects still play, but very quietly. In this scenario, the effect of distance on volume is reversed. Close sound effects are quiet while sound effects at a distance are loud. == Demonstrating the effect == To demonstrate this effect:  # Start Doom and warp to level 8 (mission 8 of any episode or MAP08). # Wake up some monsters by attacking them. # Activate the noclip cheat (IDCLIP/IDSPISPOPD) and walk outside the level, far away from any monsters. # Notice that monster growling noises can still be heard despite the distance. # Go to the sound menu and move the sound effect volume slider to minimum. # Monsters can still be heard. Travel back toward the monsters. # Notice that the volume of the monsters decreases when moving closer to them. == Technical == The cause of this is found in s_sound.c in the Doom source code:  // From _GG1_ p.428. Appox. eucledian distance fast. approx_dist = adx  ady - ((adx