Use the Javascript event function vh_ttsLoaded(args) in the HEAD section to check if the audio track is loaded:
"function vh_ttsLoaded(args){"
In this example you will see a JavaScript alert displayed when the text is ready.
When the text is loaded, play it using the sayText() command: "sayText(args, 3,1,3);"
Note: In this example we check to see if the text was loaded and only then call sayText().