  We present the second edition of the VoiceMOS Challenge, a scientific event
that aims to promote the study of automatic prediction of the mean opinion
score (MOS) of synthesized and processed speech. This year, we emphasize
real-world and challenging zero-shot out-of-domain MOS prediction with three
tracks for three different voice evaluation scenarios. Ten teams from industry
and academia in seven different countries participated. Surprisingly, we found
that the two sub-tracks of French text-to-speech synthesis had large
differences in their predictability, and that singing voice-converted samples
were not as difficult to predict as we had expected. Use of diverse datasets
and listener information during training appeared to be successful approaches.
