Mac OS X Lion is set to include a wide variety of new high quality text-to-speech voices in a multitude of languages, thanks to a long suspected partnership between Apple and Nuance, a speech technology company. The new voices are of surprisingly good quality and speak in major world languages including English, Mandarin, German, Japanese, French, Spanish, Thai, Bahasa, Portuguese, Hindi, Russian, and many more.

Want to hear some voice samples? Here’s a few different voices in WAV format, these are confirmed to be the same voices as what is in Lion DP3:

You can listen to more voices at the NextUp Nuance Sample page, but even that contains only a fraction of what is listed in Lion’s new Speech preferences. As you can hear, they are significantly improved from the current voices in Mac OS X text-to-speech, some of which are comically drone-like (Cellos anyone?).

The new voices exist as downloadable content in developer preview 3 of Lion, and were originally discovered by NetPuting and brought to light by 9to5mac (screenshot source). 9to5Mac mentions that each voice independently costs $45, suggesting Apple has reached an agreement with Nuance to license the voice technology, and they also suggest that these voices and text-to-speech technology will be a component of iOS 5.

I’ll go ahead and remind everyone that until Lion ships this summer, we don’t know for 100% certainty that these voices will be included in Mac OS X, but the evidence certainly points that way.