Support prerecorded voice instructions

[mpldr]

Is your feature request related to a problem? Please describe.
I don't have voice synthesis installed, and don't see a need to install it, but voice instructions would be nice.

Describe the ideal solution
In Setting > Voice Instructions add an option for prerecorded instructions

Ideally, this would come with a list like:

• "English – Male"
• "English – Female"
• "English – Stephen Fry"
• "German – Male"
• "German – Female"
• …

(Stephen Fry being an example for a celebrity-voice which could be hired by community members)