Speech Synthesis API Volume, Rate, and Pitch don't work - speech-synthesis

Question

Long story short, Speech Synthesis volume, rate, and pitch don't work. Is there anyone else having this issue and know how to resolve it, or am I alone?
Long story longer:
For me, Speech Synthesis volume, rate, and pitch don't work. Here is my speech function:
function speak(message, voice, callback, volume, rate, pitch, start, lang) {
if (speech) {
window.speechSynthesis.onvoiceschanged = function() {
voices = window.speechSynthesis.getVoices();
var msg = new SpeechSynthesisUtterance();
msg.voice = (typeof voice != "undefined" && voice != 0) ? voices[voice] : voices[0]; // Note: some voices don't support altering params
msg.volume = (typeof volume != "undefined" && volume != 0) ? volume : 1; // 0 to 1
msg.rate = (typeof rate != "undefined" && rate != 0) ? rate : 1; // 0.1 to 10
msg.pitch = (typeof pitch != "undefined" && pitch != 0) ? pitch : 2; //0 to 2
msg.text = message;
msg.lang = (typeof lang != "undefined" && lang != 0) ? lang : "en-US";
msg.onstart = function(event) {
if (typeof start != "undefined" && start != 0) {
start(event);
}
}
msg.onend = function(event) {
console.log(event.elapsedTime);
if (typeof callback != "undefined" && callback != 0) {
callback(event);
}
};
speechSynthesis.speak(msg);
};
}
}
However, when I call speak("Hello", 0, 0, 0.1) it outputs the exact same thing as speak("Hello"). I want to make it output the same thing but softer.
I am currently following http://updates.html5rocks.com/2014/01/Web-apps-that-talk---Introduction-to-the-Speech-Synthesis-API .

Answer 1

This is more of a comment but it could be a typo.
It looks like Speech Synthesis class has a rate property as well.
Be sure to set it on the utterance and not the speech synthesis object.
Incorrect:
speechSynthesis.rate = 2;
speechSynthesis.speak(utterance);
Correct:
utterance.rate = 2;
speechSynthesis.speak(utterance);

Answer 2

For some reason, the parameters will work if you change the language to en-EN.

Answer 3

From what I am seeing, setting these parameters only has an effect when the voice is from a local service.
As you noted, this is probably a case of not all voices supporting the ability to set parameters.

Answer 4

I am trying to do the same thing too. But i managed to make it work by adding a fullstop where I want it to slow down. I know this is not the right way to do it but it is kind of working for me
var u = new SpeechSynthesisUtterance();
u.text = 'Welcome to Handy Mandy. Lets Get Started. Say Handy Mandy.';
//u.lang = 'en-US';
//u.rate = 10;
//u.onend = function(event) { alert('Finished in ' + event.elapsedTime + ' seconds.'); }
speechSynthesis.speak(u);
Before this it