TTS syntax is not always working

[Volmark]

AnkiDroid v. 2.16.5 from github. com

This example doesn’t work. Nothing happens …
{{tts en_US:F1}}

This example works with following issues:

1. need to push the button to play but I need to play automatically
2. it plays with English pronunciation despite it Portuguese
3. the attribute “speed=0.5” doesn’t work.

{{F1}}
{{tts pt_PT speed=0.5:F1}}
Play TTS

This syntax doesn’t work
{{tts-voices:}}

???

[dae]

That syntax is currently only supported in the AnkiDroid 2.17 alpha.