In order to use your own Google Cloud Platform account to enable Wavenet voices in Read Aloud, follow these steps:
1. Login to the Google Cloud Platform console
2. Create new project (or use an existing one)
3. From the left popup menu, select API & Services -> Library
4. Find and enable the "Cloud Text-to-Speech API"
5. From the left popup menu, select API & Services -> Credentials
6. Create a new API key (or use an existing one)
7. Open Read Aloud options, in the Voice dropdown scroll to the bottom and choose "Enable Custom Voices"
8. Enter your API key into the form and click Save
You should get a green message that says "Wavenet voices are enabled".