What actually defines "pro audio"?

I am interested in hearing the how you would answer the question, what is pro audio?
I'm part of a group of graduate students music enthusiasts who are conducting research about professional audio. Part of our research involves a simple survey about the need of professional audio users. If you feel so inclined to further contribute, we would highly value your opinion and be delighted if you could take a moment and fill it out. If not, I'd still like to hear what "pro audio" means to you.

https://www.surveymonkey.com/s/3QNDY27