Sequence Voice command works on Mobile device but not on IPAD

Hello,

I have this code that works on mobile device(Iphone) but not on Ipad. Any idea why?

var labelId = "label-1";
$scope.$on('newStep', function(evt, arg)
{
$scope.setWidgetProp( labelId, "text", arg);
var labelText = $scope.view.wdg['label-1'].text;
var InstructText = labelText.substr(labelText.indexOf(")") + 1);
$scope.setWidgetProp( "label-1", "text", InstructText);
var spokenText = $scope.view.wdg["label-1"].text;
var msg = new SpeechSynthesisUtterance(spokenText)
window.speechSynthesis.speak(msg);

});

Avinash