  This paper presents a free Japanese singing voice corpus that can be used for
highly applicable and reproducible singing voice synthesis research. A singing
voice corpus helps develop singing voice synthesis, but existing corpora have
two critical problems: data imbalance (singing voice corpora do not guarantee
phoneme balance, unlike speaking-voice corpora) and copyright issues (cannot
legally share data). As a way to avoid these problems, we constructed a PJS
(phoneme-balanced Japanese singing voice) corpus that guarantees phoneme
balance and is licensed with CC BY-SA 4.0, and we composed melodies using a
phoneme-balanced speaking-voice corpus. This paper describes how we built the
corpus.
