We present a method for cross-lingual training an ASR system using absolutely
no transcribed training data from the target language, and with no phonetic
knowledge of the language in question. Our approach uses a novel application of
a decipherment algorithm, which operates given only unpaired speech and text
data from the target language. We apply this decipherment to phone sequences
generated by a universal phone recogniser trained on out-of-language speech
corpora, which we follow with flat-start semi-supervised training to obtain an
acoustic model for the new language. To the best of our knowledge, this is the
first practical approach to zero-resource cross-lingual ASR which does not rely
on any hand-crafted phonetic information. We carry out experiments on read
speech from the GlobalPhone corpus, and show that it is possible to learn a
decipherment model on just 20 minutes of data from the target language. When
used to generate pseudo-labels for semi-supervised training, we obtain WERs
that range from 32.5% to just 1.9% absolute worse than the equivalent fully
supervised models trained on the same data.Comment: Submitted to Interspeech 202
