X-ray Imaging and Computed Tomography for the Identification of Geometry and Construction Elements in the Structure of Old Violins

Abstract

Numerous studies on heritage violins have shown that there are a number of factors that contribute to the acoustic quality of old violins. Among them are the geometric shape of the violin, the thickness of the tiles, the arching of the tiles, the dimensions and position of the bass bar, the size and position of the acoustic holes. Thus, the paper aims to compare the structural and constructive elements of old violins made in various famous violin workshops (Stainer, Klotz, Leeb, Babos Bela), using nondestructive and noncontact techniques based on image analysis. The violins that were studied date from 1716 to 1920, being in good condition, most of them being used by artists from the Brașov Philharmonic of Romania. In the first stage of the study, the violins were optically analyzed and scanned to identify the structure of the resonant wood, using the WinDENDRO Density 2007 program. X-ray imaging and computed tomography (CT) were also used. Combining the types of analyses, capitalizing on the expertise of violin producers and the knowledge of researchers in the field, valuable data on the geometric and constructive characteristics of old violins were extracted.

Signature Modes of Old and New Violins with Symmetric Anatomical Wood Structure

“…The same violins were studied in previous research from the points of view of anatomical structures of their wood and of their constructive features [40]. All the violins studied are constructively intact, being used in musical activities by their owners.…”

“…For each violin, the signals from two successive tests were taken. The quality factor Q is the ratio between the resonance frequency and the variation of the frequency at 0.707 times the amplitude of the forced vibration signal (1) [40,41].…”

“…For the maple boards used in the construction of the back of the violin, only the width of the annual rings and wavelength of the curly fibers were measured in accordance with [41][42][43] (Figure 3). By analyzing the anatomical models of wood from the construction of old violins, it is possible to date and even locate the source of origin of the tree from which the wood was harvested, by reporting the measurements to an international database [40][41][42][43]. The technique is known as dendrochronology and is based on measuring and verifying the series of rings that have been cross-dated with each other with the WinDENDRO Density 2007 image-analysis system (WinDENDRO 2007), adopting a threshold of 0.60 as Gleichläufigkeit correlation coefficient [44].…”

“…Refs. [39,40] performed a dynamic analysis of an old historical violin, identifying the cavity modes (A0, A1), corpus modes (CBR or C bouts rhomboidal), and main body resonance (B1− and B1+). Some studies on the modal parameters of unvarnished violins ("white") and varnished violins were made, the "white" instruments being very similar.…”

Special Issue of “Material Analysis in Cultural Heritage”

“…Another important aspect of culture, past or present, is music. Stanciu et al studied the art of making ancient violins [ 13 ]. The authors investigated the structure and density of wood.…”