In Job Engine, espeak talks on top of itself.

[JamesNewton]

the exec function returns instantly and continues to run espeak in the background, so that it's possible to call speak again. If speak is called multiple times, all the message appear on top of each other.

We fixed this once,
HaddingtonDynamics/Dexter#72 (comment)
but the fix wasn't incorporated and the code in DDE has changed enough that it needed to be re-implemented. I know the code below is working on my robot using job engine version 3.5.2, and I /think/ this will not cause problems going forward.

var to_speak = []
function speak({speak_data = "hello", volume = 1.0, rate = 1.0, pitch = 1.0, lang = "en_US", voice = 0, callback = null} = {}$
    if (arguments.length > 0 && speak_data != null) {
      var speak_data = arguments[0] //, volume = 1.0, rate = 1.0, pitch = 1.0, lang = "en_US", voice = 0, callback = null
      //out("speak_data:"+speak_data);
      }
    var text = stringify_for_speak(speak_data)
    if(window.platform == "node"){
      if (speak_data != null) { //new speech text
        let speak_cmd = "espeak \"" + text + "\" -a "+ (volume*200) + " -p " + (pitch * 50) + " -s " + (rate * 37 + 130)
        to_speak.push(speak_cmd)
        //out("saylater:"+speak_cmd)
        }
      else { //finished speaking prior text
        if (to_speak.length > 0) { //say what's on the stack, dump, and call again with null
          //out("saying: "+to_speak[0])
          exec(to_speak[0], function(){ to_speak.shift(); speak({speak_data:null}); })
          }
        else {
          //out("done saying");
          if (callback) callback();
          }
        }
      if (to_speak.length == 1) { //last one
        //out("lastword:"+to_speak[0])
        exec(to_speak[0], function(){ to_speak.shift(); speak({speak_data:null}); })
        }
      }
    else {
        var msg = new SpeechSynthesisUtterance();
//.... same from here down.