Update on what's been doing.
1) Spent last few weeks studying noise. How to detect, remove, identify. Lot more complicated than thought. There's hard 'g', 'p' / soft 'h' / laugh volume micro-bursts / up-puh~ / snick / cough / breath / style of speech / A~Ad Avis / stress / serious / enunciate / guffaw / English-isms / button push / room ambient / slur / bah~~ vs bah! (brief) / unknown mouth sloshing / whistle / hold time of 'T'he lock / bac-k!-uh. Treating this as non-noise - voice technique.
And annoying pop + click.
Seems to affect 16-bit ADPCM 11025 much more than 22050 16-bit. Hard part is not over-scrubbing and damaging any raw voice (see above). Cut too much noise and it sounds sharp, briefer - seems phony compared to uncut parts in same clip.
Experimented with a new method that removes small bumps that come out as pops, excessive noise that's far away from voice data. Will be used on QG4 AUD (nearly done) ~ 102 overflow peaks corrected. Hand cleaned other warts.
KQ7 AUD patch should be discarded - little good and likely small minor damage. PQ4 AUD probably has some minor 'scratching' - might redo cleaning procedure some other day with new safer method.
Did try playing with the Sierra low-pass filter used in Torin's Passage for other pcm clips. Sounds blurry, distant. Removes too much noise, dirt. Doesn't have same 'faithful' feeling and destroys unique speech quirks of John Rhys-Davies. So I'm not using it (and giving option to remove it from future SCI2 games). Using linear interpolation adds too much aliasing, voice band bursts - sounds worse.
So~~. QG4 + LSL6 AUD basically done for release. 16-bit --> 8-bit DAC fix kits coming also (Pepper, LSL6, QG4, KQ7).
2) Tandy DAC w/ Freddy Pharkas
FP uses 16-bit WAVE format sfx (instead of SOL). Driver gets confused and treats everything as raw 8-bit pcm. So heavy distortion.
Have to rewrite that part of driver to accept new style. Not started.
3) Jones
Haven't even got a chance to look yet. File is unusually large > 32KB. Looks strange.
4) New games to look at
Torin's Passage, Slater and Charlie, Mother Goose (later versions), Jones.
5) 8-bit AUD
Have to construct new peak overflow methods. Not started.