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Journal Article Open Access

Improved Real-Time Monophonic Pitch Tracking with the Extended Complex Kalman Filter

Authors: Das, Orchisama; Smith III, Julius O.; Chafe, Chris

Journal of the Audio Engineering Society · Volume 68 · Issue 1/2 · pp. 78–86 · January 2020

Abstract

This paper proposes a real-time, sample-by-sample pitch tracker for monophonic audio signals using the Extended Kalman Filter in the complex domain, called an Extended Complex Kalman Filter (ECKF). It improves upon the algorithm proposed in a previous paper by fixing the issue of slow tracking of rapid note changes. It does so by detecting harmonic change in the signal, and resetting the filter whenever a significant harmonic change is detected. Along with the fundamental frequency, the ECKF also tracks the amplitude envelope and instantaneous phase of the input audio signal. The pitch tracker is ideal for detecting ornaments in solo instrument music such as slides and vibratos. The improved algorithm is tested to track pitch of bowed string (double-bass), plucked string (guitar), and vocal singing samples. Parameter selection for the ECKF pitch tracker requires knowledge of the type of signal whose pitch is to be tracked, which is a potential drawback. It would be interesting to automatically pick the optimum set of parameters given an audio signal by training on instrument specific datasets.

Details

Publication
Journal of the Audio Engineering Society
Volume
68
Issue
1/2
Pages
78–86
Publication date
January 6, 2020
Affiliation
Center for Computer Research in Music and Acoustics, Stanford University, Stanford, CA, USA (See document for exact affiliation information.)
Type
Journal Article