Solo to a capella conversion - Synthesizing vocal harmony from lead vocals

This paper presents our work in the automatic synthesis of vocal harmony. Existing innovations either allow for dissonances (i.e. non-harmonious or clashing intervals) at various locations or require some musical ability of the user. We have developed a method that is able to automatically synthesize vocal harmony even for ordinary singers with a poor sense of harmony and rhythm. We have evaluated our method by means of spectrogram comparison as well as subjective listening tests. A spectrogram comparison of our method and two popular existing methods against that of the human voice shows that our method is least dissonant and most similar to natural human vocals. Subjective listening tests conducted separately for experts and non-experts in the field confirm that the vocal harmony synthesized using our method sounds the best in terms of consonance, inter-syllable transition, as well as naturalness and appeal.