APPROXIMATE NOTE TRANSCRIPTION FOR THE IMPROVED IDENTIFICATION OF DIFFICULT CHORDS – Matthias Mauch and Simon Dixon
This is a new chroma extraction method using a non-negative least squares (NNLS) algorithm for prior approximate note transcription. Twelve different chroma methods were tested for chord transcription accuracy on popular music, using an existing high- level probabilistic model. The NNLS chroma features achieved top results of 80% accuracy that significantly exceed the state of the art by a large margin.
We have shown that the positive influence of the approximate transcription is particularly strong on chords whose harmonic structure causes ambiguities, and whose identification is therefore difficult in approaches without prior approximate transcription. The identification of these difficult chord types was substantially increased by up to twelve percentage points in the methods using NNLS transcription.
Matthias is an enthusiastic presenter who did not hesitate to jump onto the piano to demonstrate ‘difficult chords’. Very nice presentation.