No promises, but try this:
Settings -> Languages & input -> Text-to-speech output -> Gear icon (alongside "Google Text-to-speech Engine" -> Install voice data - > English (United States) -> Voice set 1.
Test the output using Settings -> Languages & input -> Text-to-speech output -> Listen to an example.
This changes the Text-to-speech voice but *does not* change the voice feedback from, for example, an OK Google search.