Archive
IJMSTA - Vol. 5 - Issue 2 - July 2023
ISSN 2612-2146
Pages: 9
A High-Resolution Spectrum Editor for Real-Time Modification of String Instrument Impulse Responses
Authors: Patrick Gaydecki, Erdem Atbas
Categories: Journal
Abstract - The measured impulse responses of both bowed and plucked string instruments are widely used to aid in the analysis of timbre, and in some cases, the design of instrument bodies. More recently, they have been used with real-time hardware to mimic, through convolution, the sound of the acoustic instrument when fed by the signal generated by its electric equivalent. A unique software tool has been developed that allows the performer or user to modify any given impulse response by interactively adjusting its spectrum, i.e. its frequency response. Using a mouse or mouse pad, a region is selected, and its amplitude adjusted via the scroll-wheel or equivalent pad operation. The algorithm has an arbitrary frequency discrimination, thereby enabling the amplification or suppression of bands with high precision whilst leaving adjacent bands unaffected. The algorithm also incorporates shaping options to blend the edited band, yielding a smooth transition with neighbouring harmonics. End-point artefact in the revised impulse response (a consequence of spectrum-based signal processing) is suppressed using either double-length Fourier synthesis or direct envelope shaping in the time domain. As the spectrum is edited, the revised impulse response is instantaneously generated, which may now be downloaded into suitable hardware for real-time performance evaluation. This software tool has proven useful for performers, instrument makers and researchers in the field of musical psychoacoustics.
Keywords: Instrument body impulse response, Equalization, Digital convolution, Spectrum modification, Frequency response
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