Noise removal... very noisy recording

Hi guys. I have been reading for a while, and have tried a few of the tips on here to achieve this.
So it makes sense what I am trying to do, I will explain a situation.
There was a very important meeting in which 5 people attended. Some items that were mentioned have very important ramifications down the line.
The problem was, the recording of this was terrible. It was held in a very busy location, with poor acoustics. There is a lot of ambient noise. Other voices, echos etc. Machinery and cars too. Lol.
There is a continual sound under all the other speaking.

What I want to know is, is it possible to remove alot of the rubbish to make the needed voices clearer? not perfect, but clear enough for most people to hear and understand.
I have tried the noise removal tool but it does not work. All i get is, this strange “space chamber” popping and pinging noises. I have tried different zoom levels, selections, and different times and volumes.
It does not seem to work so well. Any ideas or help would be much appreciated!

Any advanced technique should be done under Audacity 1.3. Audacity 1.2 tools were very basic and some just didn’t work very well.

It was held in a very busy location, with poor acoustics. There is a lot of ambient noise. Other voices, echos etc. Machinery and cars too.

That’s pretty much the death of the recording. Noise Reduction will not remove or even significantly affect any of those problems.

You might be able to use the equalizer or cut filters to dig a little intelligence out of the mess.

Effect > Hi Pass Filter, 300 Hz.
Effect > Low Pass Filter , 3000Hz.

Experiment with different numbers.

Koz