Air Traffic Control Speech Issues
From X-Plane Wiki
The first thing to check when diagnosing an ATC speech problem is the computer’s speech synthesis software. Users can download the Speech Synthesis SDK v5.1 if they are not certain that speech synthesis software is currently installed. Download the file SpeechSDK51.exe (found near the bottom of the page). This is a self-extracting archive. When it is run, it extracts all of the files to the hard drive that are needed to install Microsoft speech. Be sure to choose a location to extract the files to that can be found later. When all of the files are extracted, the installation is not complete. To complete it, the user must browse to the location of the extracted files and run Setup.exe. Once the setup is complete, users may delete the extracted files so they do not continue to take up hard drive space.
Once Speech 5 is installed, go into X-Plane, open the Settings menu, and click Sound. In the box at the bottom, you should see the message "Speech synthesis for air traffic control voice output is installed on this machine." If you do not see this, then the installation has not been completed. To hear the speech, hit the Enter key while flying. You will see various things appear on the windshield for you to choose.
If you do that and you still get no audio ATC in X-Plane, then it is likely a compatibility problem between multiple technologies. We have been working extensively with Microsoft on this. We have determined that X-Plane is not the culprit. The problem is that the sound card cannot play a WAV file (sound effect) at the same time that it plays speech. We tested this by compiling X-Plane with the sound effects disabled and the speech started working.