Text to speech? To my knowledge, there's no such thing in the Sailfish platform. I once tried espeak, which someone had packaged and distributed at OpenRepos. On about the fifth call, it crashed the whole OS, so it didn't seem ready for use. It would be fairly easy for me to add TTS calls to navigation, finding a working TTS library/program is the difficult part.
espeak --stdout "Some text" | gst-launch-1.0 -q fdsrc ! wavparse ! audioconvert ! pulsesink
flite -t "Some text" -o /tmp/out.wav && gst-launch-1.0 -q filesrc location=/tmp/out.wav ! wavparse ! pulsesink