What you are describing sounds like it may be dithering noise, or rather noise from not dithering. You MIGHT be able to mask it in Vegas or forge? Noise reduction should help if you can find a few VERY tight selections.

Yes, try NR, like the man said. Also, I've been lucky using the Paragraphic EQ in Sound Forge, the preset called reduce 60 Hz hum - 4 stacked filters. Obviously you'll move the Hz to a much higher setting.
I think I've heard that kind of noise. Didn't know it was dithering - but that'll explain its behaviour, I guess.
Good luck.
Tor

Bob, when you said it was cut in Premiere, do you have access to the original footage - at least to check whether it was from camera or later.

Bob - I've emailed you . . G

SPOT et al,
it's not noise in the sense that it's something constant, definately not there in silence, it's more like a harsh resonance at a few KHz and it sounds like it comes off the peaks, most noticable I guess when a word ends with a stop constant.
I don't have access to the orginal footage so not a whole lot I can do about it, just curious.
However now that I've gotten into it a bit more I notice that the sound guy (he's in shot for a lot of it doing the interviews) is using a very small recording device. It has a good mic plugged into an XLR connector but the whole device fits easily in his hand. When this device is the sound source seems to be when the problem arises. I'm suspecting it records at a low bit depth / sample rate and SPOT might be on the money, this audio hasn't been properly converted.
I vaguely seem to recall hearing the same sort of thing on some phone circuits that work at low bitrate but much worse.
This isn't bad enough to reject and only really noticeable when I listen to it through the cans, they really highlight any defect in audio I find. I have noticed something similar when I used to record at 16/48 and used a LOT of compression, I'd get a certain harshness, switching to 24/48 for recording put an end to that, but this seems to be affecting the peaks more.
The wierd thing is the guys who shot it are from the radio network and having a go at video as a sideline, well the videos fine, they screwed up the audio, go figure!

Bob.

Or perhaps the sound you hear is the result of a cheap limiter or automatic gain control. Is the pitch constant or does it depend on the pitch of the "source" sound? Do try the stacked filters.
Tor

Again if it's low bit rate, low sample rate, or just not good processing, tails of audio will have zipper noise. This is aliasing, and applying a dithering filter (or having a great one built in like Vegas does) helps smooth this out.
iZotope has the best one I've heard. Very sweet.

SPOT,
I think you're right, that's exactly what it sounds like. I'll talk to the audio guy later in the week and pick his brain. Once it's rendered out onto the DVD and played back on a typical home system it doesn't sound that bad, it's when you go straight from the source AVI keeping it digital to the last moment and feeding it into cans that it sounds bad.
Anyway thanks everyone for the input, especially Grazie. I've got to get back to the vision part of this project. They sent me a few still to use for the menus etc on the DVD and very kindly sized them to 720x576 as jpeg except the things 16:9 PAL so once I've cropped the still to match the AR they look pretty sad. That bit I can fix, just means a trip to the beach.

Bob.

Itzah Pleasure ! - G

Hm,
did I say the video was fine?
Well, um, er, what's that thing called again, ah yes, lip sync. Now I thought when the interviewer had the mike pointed at him he should be the one asking the question, shouldn't he, ah maybe I'm wrong, maybe that's when we are supposed to hear the answer. But the guy giving the answers lips aren't moving!
Must be some new editing style, damn I haven't got SPOTs new book yet, must be covered in that, I can see I've still got a lot to learn.
And I used to complain when I had Ripple Edit on and Vegas somehow would slip my audio 10 seconds out of sync, well maybe those Sony guys had it right all along.

Sorry guys, I'm being sarcastic, I just needed to get this off my chest.

This is from the same mob who reject material if the video levels are 1% outside legal, boy am I going to keep a copy of this stuff!
Bob.

"Raw" and "Prawn" come to mind - Bob!

Grazie