Expanding the language coverage of speech technology has the potential to
improve access to information for many more people. However, current speech
technology is restricted to about one hundred languages which is a small
fraction of the over 7,000 languages spoken around the world. The Massively
Multilingual Speech (MMS) project increases the number of supported languages
by 10-40x, depending on the task. The main ingredients are a new dataset based
on readings of publicly available religious texts and effectively leveraging
self-supervised learning. We built pre-trained wav2vec 2.0 models covering
1,406 languages, a single multilingual automatic speech recognition model for
1,107 languages, speech synthesis models for the same number of languages, as
well as a language identification model for 4,017 languages. Experiments show
that our multilingual speech recognition model more than halves the word error
rate of Whisper on 54 languages of the FLEURS benchmark while being trained on
a small fraction of the labeled data