Changing the default voice of Android's Text To Speech

Question

I'm using the Android's Text To Speech default engine in my app, however the female's voice sounds like a woman over 40 and her voice is somewhat robotic.

I saw other apps that seems to use Google's built in TTS, but it sounds a lot better i.e young woman with a more natural voice.

That "natural" voice is also being used in the Android main Google Search e.g. when you press on the mic and ask a question (Siri style) like "who is the president of the US", the woman's voice will tell you the answer.

How can this voice be achieved in the code?

Basically this is what I do in my code:

    TextToSpeech tts = new TextToSpeech(this, this);
          .
          .
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    tts.setLanguage(Locale.US);
    tts.speak(text, TextToSpeech.QUEUE_FLUSH, null);

Answer 1

Here is my code to use KEY_FEATURE_NETWORK_SYNTHESIS param:

HashMap<String, String> onlineSpeech = new HashMap<>();
onlineSpeech.put(TextToSpeech.Engine.KEY_FEATURE_NETWORK_SYNTHESIS, "true");
tts.speak(speech, TextToSpeech.QUEUE_FLUSH, onlineSpeech);