How do I normalize the volume across the whole recording

Hi everybody,
I have a two-hours conference recorded and would like to normalize the volume (I don’t know if “normalize” is the proper word: what I want is to have the same volume level across the whole conference, and not as now that the voice of the speaker is higher in some parts and lower in others). How do I do that in Audacity?
Thank you very much for your help!

Chris’s dynamic compressor

See: Chris’s Compressor, above.

I change the compression from 0.5 to 0.77, but I don’t change any other settings. Excellent volume leveler. If you’re happy with it, post a note on his web site.