I went searching on Google for info about 16mm audio. It led me back to this site where a thread said this:
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Heard back from Belbucus regarding the mono soundtrack:
While it might yield a useful reference, 16mm soundtracks have a fairly limited frequency response – around 150 to 5000 Hz with a dynamic range of about 40 dB. A 35mm Academy mono optical track is more like 45 to 8000 Hz with a dynamic range of around 48 dB.
From wikipedia, the linear track on a VHS tape has a frequency response of 100 to 10000Hz, so was probably a better source for the audio - certainly in terms of high-frequency content.
http://originaltrilogy.com/forum/topic.cfm/Puggo-GRANDE-16mm-restoration/topic/9752/page/2/
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So, I'm wondering if it would be just a waste of effort when you can get the soundtrack off of the PAL or the Jap/HK laserdisc.