Sound Packs.
You can set up 1 sound pack at a time with Tube Sim.
The files should be placed in the soundPack folder provided and be in the wav file format, Its suggested that files should be 16 bit 44100 HZ.
The files should be named:
moveUnderground.wav
moveOverground.wav
moter.wav
moterOverground.wav
horn.wav
doorOpen.wav
doorClose.wav
doorOpen_external.wav
doorClose_external.wav
outsideAmbiance.wav
outsideAmbiance_external.wav

Some or all of the above files can be provided. Any other files in this folder will be ignored and the defaults will be used.
Those files with a "_external" at the end of the file are used when changing point of view to the external POV.
If you come up with a good sound pack please contact nick@ndadamson.com with details and a link to the pack. I'll take a listen and possibly provide a sound pack area on ndadamson.com and include your packs. Please note, its intirely my choice which packs get listed or not, generally i'll make this choice on sound quality and how well it works with in the game.
