Thank you kentakta -
I am sure I have not set up something right. By your response to me, can I assume that you are using the same engine located in the android system root (\VocalizerTTS) and have that engine selected in the Android TTS system Language and Input > Text-to-speech settings? What voice are you using in the Android TTS settings?
The English-Aus_universal_unisex_andTTS-Boki_Srb_v.1.zip is then located in the iGP\content\voice folder.