You can even use Google Translate's text to speech API in whatever learning program you build for yourself:

  GET https://translate.google.com/translate_tts?ie=UTF-8&tl=zh_CN&client=tw-ob&q=<url encoded text>

This returns an audio/mpeg (mp3) response. Change the language code as appropriate.

It's not the most natural sounding TTS engine, but it's free, unauthenticated and trivial to use.