event onboundary doesn't work on Phonegap

        Hi, this code bellow work on browser, but when I build the apk and run it the app just speak but not appear the alert.

        var u = new SpeechSynthesisUtterance();
        var txt = "Hello word";
        u.text = txt;
        u.lang = 'en-US';
        speechSynthesis.speak(u);
        u.onboundary = function(event){
          alert(event.name);
        };
