Sound quality assessment of wood for xylophone bars
Authors: Aramaki M., Bailleres H., Brancheriau L., Kronland-Martinet R., Ystad S.
Publication Date: April 2007
Journal: Journal of the Acoustical Society of America (JASA) (Vol 121(4), pp: 2407-2420, 2007)
Xylophone sounds produced by striking wooden bars with a mallet are strongly influenced by the mechanical properties of the wood species chosen by the xylophone maker. In this paper, we address the relationship between the sound quality based on the timbre attribute of impacted wooden bars and the physical parameters characterizing wood species. For this, a methodology is proposed that associates an analysis-synthesis process and a perceptual classification test. Sounds generated by impacting 59 wooden bars of different species but with the same geometry were recorded and classified by a renowned instrument maker. The sounds were further digitally processed and adjusted to the same pitch before being once again classified. The processing is based on a physical model ensuring the main characteristics of the wood are preserved during the sound transformation. Statistical analysis of both classifications showed the influence of the pitch in the xylophone maker judgement and pointed out the importance of two timbre descriptors: the frequency-dependent damping and the spectral bandwidth. These descriptors are linked with physical and anatomical characteristics of wood species, providing new clues in the choice of attractive wood species from a musical point of view.
Digital tuning of impact sounds
Original sounds can be modelled and tuned using analysis-synthesis processes. Two examples corresponding to frequency transpositions toward higher and lower frequencies are given below:
Coula edulis Baill.
Faucherea parvifolia H.Lec.
Sounds used for the classification test C3 (sounds with identical pitches)
(photo credits: L. Brancheriau, P. Detienne and D. Guibal)