static File espeakToWAV(S text, S voice) {
  File wav = prepareCacheProgramFile("Computer Voices/eSpeak/" + uniqueFileNameUsingMD5_80_v2(appendIfNempty(voice, "|") + text) + ".wav");
  if (fileEmptyOrNotThere(wav))
    espeakToWAV(text, voice, wav);
  ret wav;
}
  
static File espeakToWAV(S text, S voice, File wav) {
  backtick("espeak "
    + "-w " + platformQuoteOpt(wav)
    + (nempty(voice) ? "-v " + platformQuoteOpt(voice) : "")
    + platformQuote(text));
  ret wav;
}