No sound at all and the console shows lots of these messages:

    24:4 Uncaught TypeError: Cannot read properties of undefined (reading 'lang')
    at 24:4:132

Which seems to be this line:

    m.lang = e[(Math.random() * e.length) | 0]["lang"];

Another observation: You write:

    m = new SpeechSynthesisUtterance;
    m.text = "Hello";
    speechSynthesis.speak(m);

    Run that JS and your computer will speak to you!

But when I paste those 3 lines into the console, that also does not produce any sound here. I tried in Chromium and Firefox, both on Linux.