Estimating Pickup and Plucking Positions of Guitar Tones and Chords with Audio Effects

Zulfadhli Mohamad; Simon Dixon; Christopher Harte
DAFx-2017 - Edinburgh
In this paper, we introduce an approach to estimate the pickup position and plucking point on an electric guitar for both single notes and chords recorded through an effects chain. We evaluate the accuracy of the method on direct input signals along with 7 different combinations of guitar amplifier, effects, loudspeaker cabinet and microphone. The autocorrelation of the spectral peaks of the electric guitar signal is calculated and the two minima that correspond to the locations of the pickup and plucking event are detected. In order to model the frequency response of the effects chain, we flatten the spectrum using polynomial regression. The errors decrease after applying the spectral flattening method. The median absolute error for each preset ranges from 2.10 mm to 7.26 mm for pickup position and 2.91 mm to 21.72 mm for plucking position estimates. For strummed chords, faster strums are more difficult to estimate but still yield accurate results, where the median absolute errors for pickup position estimates are less than 10 mm.