Automatic Transcription of Diatonic Harmonica Recordings

Abstract

This paper presents a method for automatic transcription of the diatonic Harmonica instrument. It estimates the multi-pitch activations through a spectrogram factorisation framework. This framework is based on Probabilistic Latent Component Analysis (PLCA) and uses a fixed 4-dimensional dictionary with spectral templates extracted from Harmonica's instrument timbre. Methods based on spectrogram factorisation may suffer from local-optima issues in the presence of harmonic overlap or considerable timbre variability. To alleviate this issue, we propose a set of harmonic constraints that are inherent to the Harmonica instrument note layout or are caused by specific diatonic Harmonica playing techniques. These constraints help to guide the factorisation process until convergence into meaningful multi-pitch activations is achieved. This work also builds a new audio dataset containing solo recordings of diatonic Harmonica excerpts and the respective multi-pitch annotations. We compare our proposed approach against multiple baseline techniques for automatic music transcription on this dataset and report the results based on frame-based F-measure statistics.