Ajax request: Refused to set unsafe header

I am trying to play an audio using Google Text-To-Speech. Therefore I need to post a request to their endpoint with the Referer and the User-Agent properly set. This call should return an MP3 that I can play.

However, I get Refused to set unsafe header errors. This is my code. How can I do this?

          $.ajax({
            url: 'http://translate.google.com/translate_tts?ie=UTF-8&q=Hello&tl=en&client=t',
            beforeSend: function(xhr) {
                 xhr.setRequestHeader("Referer", "http://translate.google.com/");
                 xhr.setRequestHeader("User-Agent", "stagefright/1.2 (Linux;Android 5.0)");
            }, success: function(data){
                el.mp3 = new Audio(data);
                el.mp3.play();
            }
          });

You can't. It is impossible.

The specification requires that the browser abort the setRequestHeader method if you try to set the Referer header (it used to be that User-Agent was also forbidden but that has changed)..

If you need to set Referer manually then you'll need to make the request from your server and not your visitor's browser.

(That said, if you need to be deceptive about the user agent or referer then you are probably trying to use the service in a fashion that the owner of it does not want, so you should respect that and stop trying).

Note that while jQuery wraps XHR, the same rules apply to fetch.