“speechSynthesis is not defined” Uncaught ReferenceError in Oculus browser

Text to Speach API demo

function speak() { speechSynthesis.speak(new SpeechSynthesisUtterance("hello world")); }

works in Chrome on Windows and Android but I get "Uncaught ReferenceError: speechSynthesis is not defined" in the Oculus browser. Can I use TTS API in the Oculus browser?