You can refer to
http://www.cs.umb.edu/~eckhouse/cs444/QuickC/qc25.zip

I found the source code of .VOC player.
Extract attached zip file and run PLAYVOCD.EXE
You should extract ESCAPE2.VOC into C:\MUSIC
Unfortunately(?), emulating ESCAPE2.VOC is fine.
I haven't find NOT-WORKING VOC file yet.

As I memtioned above, at http://ourworld.compuserve.com/homepages/Rocc … zo/rutils20.zip
you can download RUTILS 2.0
You can run DEMO\SOUND\samples.exe or UTILS\playrsb.exe
playrsb is more tiny, so I disassembled it like this:
Debug playrsb.exe laserzap.rsb
It is very strange!! It doesn't contain any DSP intializing code!!
It contains only one OUT instruction:
55) push bp
8BEC) mov bp, sp
8B5606) mov dx, [bp+06]
8A4608) mov al , [bp+08]
EE) out dx, al (OUT 022C,08)
B400) mov ah, 00
5D) pop bp
CB) retf

I searched the web, but I still don't know what DSP command 08 means. Do you guys have some idea?
I consulted next sites:
http://faculty.petra.ac.id/irwankj/ap2/sb16doc.html
http://the.earth.li/~tfm/oldpage/sb_dsp.html
http://www.chez.com/titan/DriversLinux/SBlive/hwmnl.pdf

no idea.
It's not implemented in dosbox either.

I think dsp 08 means either "0B" (as in Bravo) or that you have overflowed the buffer (EMS problems?).. try with EMS disabled and see if you get different results.
I suspect temporary buffers may be causing problems, or depending on
playback mode, pointers might need to be incremented or stay static where
they are not at the moment.

I debugged playrsb.exe on real DOS and on DOSBox.
And I am sure when I trace(i.e, step into) OUT 22C,8
I can hear the whole sound pattern(maybe it's triggering the sound).
(On DOSBox I can only hear just one 'tick' sound, but on real dos
I can hear siren about 2 seconds long.)
I know for example OUT A,1 enables DMA channel 1 and so
triggers the sound, so I guess OUT 22C,08 may does something like that.
And I can assure that it was not port 0B, it was port 08!
By the way, can you tell me what is DSP command 0B? Cause I don't
know DSP command 0B either. The meaning of OUT 22C,B??
And please let me know where I can get those information.
(I will appreciate it if you attatch some documents, or you can just
introduce some internet sites...)

p.s. I am still trying hard to find STRANGE and SIMPLE source code.
(STRANGE = WHICH I CAN NOT HEAR OR CAN HEAR ONLY JERKY SOUND
IN DOSBOX, BUT CAN HEAR SOUND WELL IN REAL DOS)

As I have already said, there is some sound problem running Nanpa2.
Of course I don't have the source code of the game.
But I attach four most important files, i.e, nanpa2.bat, play5v.com, n2ai5v.com and start.mes
To play the game, execute Nanpa2.bat
(Of course you can not play the game if any data file is missing.)
play5v
n2ai5v start.mes H D
play5v -r
start.mes contains conversation data (maybe it does not contain
sound data). play5v.com is RAM-resident program which should be
run before playing the game. n2ai5v.com is main file which loads fonts, sounds, graphics, etc.
If you analyze them, maybe you can find what's the problem of DOSBox.
Good luck.

p.f. There is some comment about ADPCM, AFAIK, GSM formats at http://www.cae.wisc.edu/~brodskye/tomes/adpcm.txt