Any way to change the default text-to-speech output voice?

[anon(924308)]

I've successfully changed the settings in my GPS app to dictate directions in the stock English UK voice, which I find much more realistic and tolerable. The English US TTS stock voice is screechy, obnoxious, and ear-grating--I can't stand it . I downloaded a TTS alarm clock (gives you the time, weather, etc) but I can't find a way to change the default voice within the app itself.

I went into my language settings and changed everything to "English UK", but that doesn't seem to have changed the system's stock TTS voice. Any way to change it to the UK voice without rooting?