HIGH-SPEED LINE-SCAN CAMERA MEASUREMENTS OF PIANO STRING MULTIPHONICS
İbrahim Atakan Kubilay, Juhani T. Vesikkala, Montserrat Pàmies-Vilà, Tuire Kuusi · 2015
Dept. of Signal Processing and Acoustics, Aalto University, Espoo, FinlandThe multiphonic playing technique is used in many different musical instruments. It causes oneor more partials to be heard alongside the fundamental. In this study, multiphonics on a grandpiano were analyzed. For this instrument, the multiphonic technique consists of using a plectrumto slightly press the piano string at a predetermined point in order to rise up the desired partials.The location of the plectrum along the string determines which partials are damped and whichare preserved. The partials that have a node at the plectrum position are more pronounced in thesound. For an artistic use of this technique, the purpose is to obtain a piano sound that could beperceived as different tones sounding together, therefore the plectrum position is adjusted so asto obtain sounds composed by many partials. In the experiments, a high-speed line-scan camerawas used to detect the motion of the piano string and audio recordings were also obtained forcomparison. The camera was equipped with an optical tube extender for better magnification forthe images to be recorded. The resulting camera output images were processed, converted intonumerical data, and analyzed in the frequency domain. The audio and camera recorded waveformsare presented for comparison, along with their spectrograms. The camera signal is cleaner andless prone to noise than the audio recording. We have observed that using the multiphonics on thegrand piano causes the damping of many of the original partials present on an open string, i.e.,allowing only a selected few to sound. It has been noticed that even the selected partials in themultiphonics were damped, resulting in softer sounds than the open string.ICSV22, Florence, Italy, 12-16 July 2015 1