Launch the PDF file:

1. Select View | Read Out Loud | Activate Read Out Loud
2. Select View | Read Out Loud | Choose either read "this page only" or "end of document"

If you want to change the voice settings:

1. Edit | Preferences | Select "Reading" listed along the left column
2. Uncheck both "use default voice" and "use default speech attributes"
3. Customize the voices as you wish