Speech output for bangle.js?

Just gave this a very quick try... Downloaded some WAV files of someone saying numbers - and converted them to 4kHz unsigned 8 bit raw files with sox 0.wav -r 4k -b 8 -c 1 -e unsigned-integer 0.raw vol 2 (on linux - but you could just use Audacity) and uploaded them using the Web IDE's storage menu.

Then ran this:

function play(txt, callback) {  
  function playChar(txt) {
    if (txt.length==0) {
      digitalWrite(D18,0);
      if (callback) callback();
      return;
    }
    var c = txt[0];
    var s = require("Storage").read(c+".raw");
    var w = new Waveform(s.length);
    w.buffer.set(s); 
    w.startOutput(D18, 4000);
    w.on("finish", function(buf) {
      playChar(txt.substr(1));
    });
  }
  analogWrite(D18, 0.5, {freq:40000});
  playChar(txt);
}

play("012"); // says 'zero' 'one' 'two'

Definitely works ok, although not loud.

Without a speaker it's more of a pain since you have to scale the output values so they're not high enough to move the vibration motor:

function play(txt, callback) {  
  function playChar(txt) {
    if (txt.length==0) {
      digitalWrite(D18,0);
      if (callback) callback();
      return;
    }
    var c = txt[0];
    var s = require("Storage").read(c+".raw");
    var w = new Waveform(s.length);
    var b = w.buffer;
    b.set(s);
    for (var i=s.length-1;i>=0;i--)b[i]/=4;
    w.startOutput(VIBRATE, 4000);
    w.on("finish", function(buf) {
      playChar(txt.substr(1));
    });
  }
  analogWrite(VIBRATE, 0.1, {freq:40000});
  playChar(txt);
}

But that could actually be done before the files are even written to flash