Soloist evaluations of six Old Italian and six new violins

Model-predicted geometry variations to compensate material variability in the design of classical guitars

Musical instrument making is often considered a mysterious form of art, its secrets still escaping scientific quantification. There is not yet a formula to make a good instrument, so historical examples are regarded as the pinnacle of the craft. This is the case of Stradivari's violins or Torres guitars that serve as both models and examples to follow. Geometric copies of these instruments are still the preferred way of building new ones, yet reliably making acoustic copies of them remains elusive. One reason for this is that the variability of the wood used for instruments makes for a significant source of uncertainty-no two pieces of wood are the same. In this article, using state-of-the-art methodologies, we show a method for matching the vibrational response of two guitar top plates made with slightly different materials. To validate our method, we build two guitar soundboards: one serving as a reference and the second acting as a copy to which we apply model-predicted geometry variations. The results are twofold. Firstly, we can experimentally validate the predictive capabilities of our numerical model regarding geometry changes. Secondly, we can significantly reduce the deviation between the two plates by these precisely predicted geometry variations. Although applied to guitars here, the methodology can be extended to other instruments, e.g. violins, in a similar fashion. The implications of such a methodology for the craft could be far-reaching by turning instrument-making more into a science than artistic craftsmanship and paving the way to accurately copy historical instruments of a high value.

A listening experiment comparing the timbre of two Stradivari with other violins

The violins of Stradivari are recognized worldwide as an excellence in craftsmanship, a model for instrument makers, and an unachievable desire for collectors and players. However, despite the myth surrounding these instruments, blindfolded players tendentially prefer to play modern violins. Here, we present a double blind listening experiment aimed at analyzing and comparatively rating the sound timbre of violins. The mythic instruments were listened to among other well regarded and not so well regarded violins. 70 listeners (violin makers of the Cremona area) rated the timbre difference between the simple musical scales played on a test and a reference violin, and the results showed that their preference converged on one particular Stradivari. The acoustical measurements revealed some similarities between the subjective ratings and the physical characteristics of the violins. It is speculated that the myth of Stradivari could have been boosted, among other factors, by the specimens of tonal superior quality, which biased favourably the judgment on his instruments and spread on all of the maker's production. These results contribute to the understanding of the timbre of violins and suggest the characteristics that are in a relationship with the pleasantness of the timbre.

Materials Engineering of Violin Soundboards by Stradivari and Guarneri

We investigated the material properties of Cremonese soundboards using a wide range of spectroscopic, microscopic, and chemical techniques. We found similar types of spruce in Cremonese soundboards as in modern instruments, but Cremonese spruces exhibit unnatural elemental compositions and oxidation patterns that suggest artificial manipulation. Combining analytical data and historical information, we may deduce the minerals being added and their potential functions—borax and metal sulfates for fungal suppression, table salt for moisture control, alum for molecular crosslinking, and potash or quicklime for alkaline treatment. The overall purpose may have been wood preservation or acoustic tuning. Hemicellulose fragmentation and altered cellulose nanostructures are observed in heavily treated Stradivari specimens, which show diminished second‐harmonic generation signals. Guarneri's practice of crosslinking wood fibers via aluminum coordination may also affect mechanical and acoustic properties. Our data suggest that old masters undertook materials engineering experiments to produce soundboards with unique properties.

Eigenfrequency optimisation of free violin plates

We discuss how the modal response of violin plates changes as their shape varies. Starting with an accurate 3D scan of the top plate of a historic violin, we develop a parametric model that controls a smooth shaping of the interior of the plate, while guaranteeing that the boundary is the same as the original violin. This allows us to generate a family of violin tops whose shape can be smoothly controlled through various parameters that are meaningful to a violin maker: from the thickness in different areas of the top to the location, angle, and dimensions of the bass bar. We show that the interplay between the different parameters affects the eigenmodes of the plate frequencies in a nonlinear fashion. We also show that, depending on the parameters, the ratio between the fifth and the second eigenfrequencies can be set to match that used by celebrated violin makers of the Cremonese school. As the parameterisation that we define can be readily understood by violin makers, we believe that our findings can have a relevant impact on the violin making community, as they show how to steer geometric modifications of the violin to balance the eigenfrequencies of the free plates.

Listener evaluations of violins made from composites

For centuries, wood, and more specifically spruce, has been the material of choice for violin top plates. Lately, carbon fiber instruments have entered the market. Some studies show that composite materials have potential advantages for making instruments [Damodaran, Lessard, and Babu, Acoust. Aust. 43, 117-122 (2015)]. However, no studies exist that evaluate violins made of different composite materials as judged by listeners. For this study, six prototype violins, differing only by the material of the top plate, were manufactured in a controlled laboratory setting. The six prototype violins were judged by experienced listeners in two double-blind experiments. In contrast to popular opinion that violins made from carbon have or lack a specific sound quality, the study provides insights in the diverse sounds and timbres violins from fiber-reinforced polymers can create. It allows an investigation of the links between the perception and the variations in material properties of the soundboards. Additionally, as neither players nor listeners are acquainted with these instruments, these results provide an interesting view on what type of qualities of violin-like sounds are preferred by listeners.

Effect of back wood choice on the perceived quality of steel-string acoustic guitars

Some of the most prized woods used for the backs and sides of acoustic guitars are expensive, rare, and from unsustainable sources. It is unclear to what extent back woods contribute to the sound and playability qualities of acoustic guitars. Six steel-string acoustic guitars were built for this study to the same design and material specifications except for the back/side plates which were made of woods varying widely in availability and price (Brazilian rosewood, Indian rosewood, mahogany, maple, sapele, and walnut). Bridge-admittance measurements revealed small differences between the modal properties of the guitars which could be largely attributed to residual manufacturing variability rather than to the back/side plates. Overall sound quality ratings, given by 52 guitarists in a dimly lit room while wearing welder's goggles to prevent visual identification, were very similar between the six guitars. The results of a blinded ABX discrimination test, performed by another subset of 31 guitarists, indicate that guitarists could not easily distinguish the guitars by their sound or feel. Overall, the results suggest that the species of wood used for the back and sides of a steel-string acoustic guitar has only a marginal impact on its body mode properties and perceived sound.

Acoustic evolution of old Italian violins from Amati to Stradivari

Amati and Stradivari violins are highly appreciated by musicians and collectors, but the objective understanding of their acoustic qualities is still lacking. By applying speech analysis techniques, we found early Italian violins to emulate the vocal tract resonances of male singers, comparable to basses or baritones. Stradivari pushed these resonance peaks higher to resemble the shorter vocal tract lengths of tenors or altos. Stradivari violins also exhibit vowel qualities that correspond to lower tongue height and backness. These properties may explain the characteristic brilliance of Stradivari violins. The ideal for violin tone in the Baroque era was to imitate the human voice, and we found that Cremonese violins are capable of producing the formant features of human singers.

The shape and design of the modern violin are largely influenced by two makers from Cremona, Italy: The instrument was invented by Andrea Amati and then improved by Antonio Stradivari. Although the construction methods of Amati and Stradivari have been carefully examined, the underlying acoustic qualities which contribute to their popularity are little understood. According to Geminiani, a Baroque violinist, the ideal violin tone should “rival the most perfect human voice.” To investigate whether Amati and Stradivari violins produce voice-like features, we recorded the scales of 15 antique Italian violins as well as male and female singers. The frequency response curves are similar between the Andrea Amati violin and human singers, up to ∼4.2 kHz. By linear predictive coding analyses, the first two formants of the Amati exhibit vowel-like qualities (F1/F2 = 503/1,583 Hz), mapping to the central region on the vowel diagram. Its third and fourth formants (F3/F4 = 2,602/3,731 Hz) resemble those produced by male singers. Using F1 to F4 values to estimate the corresponding vocal tract length, we observed that antique Italian violins generally resemble basses/baritones, but Stradivari violins are closer to tenors/altos. Furthermore, the vowel qualities of Stradivari violins show reduced backness and height. The unique formant properties displayed by Stradivari violins may represent the acoustic correlate of their distinctive brilliance perceived by musicians. Our data demonstrate that the pioneering designs of Cremonese violins exhibit voice-like qualities in their acoustic output.

Listener evaluations of new and Old Italian violins

Old Italian violins are routinely credited with playing qualities supposedly unobtainable in new instruments. These qualities include the ability to project their sound more effectively in a concert hall-despite seeming relatively quiet under the ear of the player-compared with new violins. Although researchers have long tried to explain the "mystery" of Stradivari's sound, it is only recently that studies have addressed the fundamental assumption of tonal superiority. Results from two studies show that, under blind conditions, experienced violinists tend to prefer playing new violins over Old Italians. Moreover, they are unable to tell new from old at better than chance levels. This study explores the relative merits of Stradivari and new violins from the perspective of listeners in a hall. Projection and preference are taken as the two broadest criteria by which listeners might meaningfully compare violins. Which violins are heard better, and which are preferred? In two separate experiments, three new violins were compared with three by Stradivari. Projection was tested both with and without orchestral accompaniment. Projection and preference were judged simultaneously by dividing listeners into two groups. Results are unambiguous. The new violins projected better than the Stradivaris whether tested with orchestra or without, the new violins were generally preferred by the listeners, and the listeners could not reliably distinguish new from old. The single best-projecting violin was considered the loudest under the ear by players, and on average, violins that were quieter under the ear were found to project less well.

Perceptual evaluation of violins: A psycholinguistic analysis of preference verbal descriptions by experienced musicians

In this paper, how the notion of violin quality is conveyed in spontaneous verbalizations by experienced violinists during preference judgments is investigated. The aims of the study were to better understand how musicians conceptualize violin quality, what aspects of the sound and the playing experience are essential, and what associations are formed between perceptual evaluation and physical description. Upon comparing violins of varying make and age, players were interviewed about their preferences using open-ended questions. Concepts of violin quality were identified and categorized based on the syntactic and linguistic analysis of musicians' responses. While perceived variations in how a violin sounds and feels, and consequently conceptualization structures, rely on the variations in style and expertise of different violinists, the broader semantic categories emerging from sensory descriptions remain common across performers with diverse musical profiles, reflecting a shared perception of physical parameter patterns that allowed the development of a musician-driven framework for understanding how the dynamic behavior of a violin might relate to its perceived quality. Implications for timbre perception and the crossmodal audio-tactile sensation of sound in music performance are discussed.

The acoustics of the violin: a review

To understand the design and function of the violin requires investigation of a range of scientific questions. This paper presents a review: the relevant physics covers the nonlinear vibration of a bowed string, the vibration of the instrument body, and the consequent sound radiation. Questions of discrimination and preference by listeners and players require additional studies using the techniques of experimental psychology, and these are also touched on in the paper. To address the concerns of players and makers of instruments requires study of the interaction of all these factors, coming together in the concept of 'playability' of an instrument.

Imitation, genetic lineages, and time influenced the morphological evolution of the violin

Violin design has been in flux since the production of the first instruments in 16^th century Italy. Numerous innovations have improved the acoustical properties and playability of violins. Yet, other attributes of the violin affect its performance less, and with fewer constraints, are potentially more sensitive to historical vagaries unrelated to quality. Although the coarse shape of violins is integral to their design, details of the body outline can vary without significantly compromising sound quality. What can violin shapes tell us about their makers and history, including the degree that luthiers have influenced each other and the evolution of complex morphologies over time? Here, I provide an analysis of morphological evolution in the violin family, sampling the body shapes of over 9,000 instruments over 400 years of history. Specific shape attributes, which discriminate instruments produced by different luthiers, strongly correlate with historical time. Linear discriminant analysis reveals luthiers who likely copied the outlines of their instruments from others, which historical accounts corroborate. Clustering of averaged violin shapes places luthiers into four major groups, demonstrating a handful of discrete shapes predominate in most instruments. Violin shapes originating from multi-generational luthier families tend to cluster together, and familial origin is a significant explanatory factor of violin shape. Together, the analysis of four centuries of violin shapes demonstrates not only the influence of history and time leading to the modern violin, but widespread imitation and the transmission of design by human relatedness.