I’m narrating an audiobook
Your first? We publish audiobook mastering tools and diagnostic testing.
You can also post a sample of your voice on the forum and we can do quicky diagnostics—usually much faster than ACX’s two week turnaround time.
http://www.kozco.com/tech/audacity/TestClip/Record_A_Clip.html
And, yes, you can submit a test to ACX. Do Not read a whole book and only then stop to find out if the quality is high enough.
Koz