Voice Recording Mode Confusion

[msun]

My MP4 Nanoclone has 4 different voice recording modes but very poor "pigeon English" instructions so here is my best guess at what the modes are:-

Fine REC, wav format, better sound quality
Bit Rate 32kbps, Audio sample size 4 bit, Audio sample rate 8kHz, Channels 1 (mono) IMA ADPCM 2x estimated free space

Long REC, act format, worse sound quality, ACT Format - Conversion Required.
Bit Rate 128kpbs, Audio sample size 16 bit, Audio sample rate 8kHz, Channels 1 (mono) PCM 1x estimated free space

Fine VOR, wav format (voice-operated recording, automatically pause when no sound).
Bit Rate 32kbps, Audio sample size 4 bit, Audio sample rate 8kHz, Channels 1 (mono) IMA ADPCM 2x estimated free space

Long VOR, act format, - Conversion Required.
Bit Rate 128kpbs, Audio sample size 16 bit, Audio sample rate 8kHz, Channels 1 (mono) PCM 1x estimated free space

Note:- act audio format has to be converted by the program provided on the mini CD to wav format.

So I find it odd that the better quality gives more estimated free space than the worse sound quality. Perhaps it is do do with more effecient storage in act file format?

I also notice that the IMA ADPCM wav files cannot be opened by some programs such as "Polderbits Sound Editor" or "Nero Wave Editor" (get an error message) whereas converted ACT files can be opened without problem. So I wonder how I can edit the IMA ADPCM wav files...

Any further explanation or other comment would be most welcome.

Cheers from Mike