I just received a new HTC One Windows 8.1 phone with Cortana installed - although it does indicate "Beta". While Cortana responds to text input, it does not "hear" me speak, and I do not hear Cortana speaking. I've looked through the various settings and can't seem to find any root cause for the lack of audio input or response. Any ideas or assistance?
I take it that talking on the phone works fine? I take it you raised the volume at the time Cortana replied? Try a soft reset and if that doesn't work sounds like a defective phone.