In the media library, right-click on the video and choose Extract audio
OptionAdd the video to the timeline, go to Produce and save it as an audio file XEON-E5-2680 v4 / Mem. 16GB DDR4
M.2 NVME 512Gb / 2-SSD Sata3 1TB
AMD RX570 / Display Philips 272V8
Windows 11_64Pro / PD22/365

Quote In the media library, right-click on the video and choose Extract audio
OptionAdd the video to the timeline, go to Produce and save it as an audio file

Thanks for this. I ended up doing it the second way you mention. However I deleted video channel first then then produced the audio channel only and saved as a mono wav file. I then opened it in an audio software program I have to duplicate the channel onto the stereo channel. It worked out great but such a long process to go through. I'm surprised PD doesn't have a more sophisticated audio editor to allow this to be done within PD (or am I missing something?)

Cheers again for the help.

Copy the audio from one channel to the other to have mono audio on the 2 channels.
In a video with many segments, I edit the entire video first.
Produce only audio in WAV, maximum quality.
Add this file to another track and disable the audio track linked to the video.
Option, add the new audio over the audio of the video and choose to overlay.
You can do it before or after producing the video
If you do later, use SVRT to avoid re-encoding the video.
How do I do this in AudioDirector
XEON-E5-2680 v4 / Mem. 16GB DDR4
M.2 NVME 512Gb / 2-SSD Sata3 1TB
AMD RX570 / Display Philips 272V8
Windows 11_64Pro / PD22/365

Quote Copy the audio from one channel to the other to have mono audio on the 2 channels.
In a video with many segments, I edit the entire video first.
Produce only audio in WAV, maximum quality.
Add this file to another track and disable the audio track linked to the video.
Option, add the new audio over the audio of the video and choose to overlay.
You can do it before or after producing the video
If you do later, use SVRT to avoid re-encoding the video.
How do I do this in AudioDirector

Thanks for the video explanation, it really helped me a lot. I don't have the Audiodirector software so I'll have to do it the long way I described. I have a couple of audio editing applications so purchasing the PD version would be surplus to my needs although it would make everything 'in house' I guess.
Of more importance to me right now is getting to know what SVRT is? As I am new to video editing, I think I need to do a little research on this.
Thanks again for your help, its greatly appreciated.

You may want to search the terms smart rendering and hardware encoding on the internet to see how it applies to video editing. It means a possible speedup.