Hi
Is it possible to correct an upward inflection in a voice? On the recording that I’m working with, the subject speaks almost with an Aussie twang where a statement will sound like a question. Is it fixable?
Thanks 
The Sliding Time scale / Pitch Shift effect can counter the pitch change (http://manual.audacityteam.org/o/man/sliding_time_scale_pitch_shift.html) but it will probably sound weird. Voices are extremely complex and human hearing is highly attuned to tiny subtleties within the sound of a voice. Within an inflection there are many subtle changes occurring as well as the change in pitch - slight changes in timing, frequency, resonance, timbre… So the short answer is that you probably can’t fix it in a convincing way.
http://en.wikipedia.org/wiki/High_Rising_Terminal
There are free autotune plugins which work in Audacity which can limit the range of frequencies voice can occupy , even make speech monotone , but the processed sound is robotic/computery, it wouldn’t pass for normal speech.