My goal is to use a synthetic voice in a Skype call. This could be used in a scenario such as being in two meetings at once (one local, one remote) and not being able to speak out loud (in the local meeting).
My current attempt is to use PulseAudio Volume Control (pavucontrol) to set the monitor audio of some headphones as an input for Skype, which is recognised by PulseAudio Volume Control as a recording program. I then can use Festival to general the synthetic voice. This does work, but the sound produced in the remote meeting then immediately loops back to me, into the monitor audio stream of the headphones and then back into Skype as an input! So, it's an echo problem.
I need something more direct. How could I pipe the audio of the synthetic voice into Skype as an input directly?