High quality Text-to-Speech powered by WaveNet is now available
HD Text-to-Speech from Google powered by WaveNet is now available to all our developers, US English only at the moment, but more languages to come soon. See the VoiceList.Google.*_Wavenet_* languages for details.
P.S. Please keep in mind that premium text-to-speech is a paid feature, see pricing for more infomation.