I'm going to say that he does not hear the whole file play for the explosion, only the initial sound, the crescendo, and then as it starts to fade out, it quits playing about 5 seconds too soon.
Belmondo, the game uses different files when your submarine is under water, and they would sound slightly muted, and quit sooner than the sound you hear when on the surface. Also, the audio in the game is generally a 44.1kHz, the same as CD audio. If you've been watching movies on your computer, the Windows audio stream might be set to 48kHz, and Windows might not be re-setting it, so check that first. You might also have a memory issue, or something playing in the background on your computer that is interfering with the game. Also, do not shell-out to Windows with the <Alt><Tab> key combination while the game is running.
The game is more than capable of playing multiple audio files, of varied types at one time, so you shouldn't have audio cutting off, unless it was edited that way. If it is one particular file that does the same thing every time, then find the file in the Sounds folder, and play it directly from there, and see if maybe it is the file itself that is messed-up. You would look for a file like "P06_#Splinter_explosion_
hyd.wav" - that "hyd" is the underwater stuff.
