Semi-supervised Lyrics and Solo-singing Alignment

We propose a semi-supervised algorithm to align lyrics to the corresponding singing vocals. The proposed method transcribes and aligns lyrics to solo-singing vocals using the imperfect transcripts from an automatic speech recognition (ASR) system and the published lyrics. The ASR provides time alignment between vocals and hypothesized lyrical content, while the non-aligned published lyrics correct the hypothesized lyrical content. The effectiveness of the proposed method is validated through three experiments. First, a human listening test shows that 73.32% of our automatically aligned sentence-level transcriptions are correct. Second, the automatically aligned sung segments are used for singing acoustic model adaptation, which reduces the word error rate (WER) of automatic transcription of sung lyrics from 72.08% to 37.15% in an open test. Third, another iteration of decoding and model adaptation increases the amount of reliably decoded segments from 44.40% to 91.96% and further reduces the WER to 36.32%. The proposed framework offers an automatic way to generate reliable alignments between lyrics and solosinging. A large-scale solo-singing and lyrics aligned corpus can be derived with the proposed method, which will be beneficial for music and singing voice related research