A necessary condition for double-decay envelopes in stringed instruments

Measurements of body vibration characteristics of five different stringed musical instruments have been used to address the question of whether and when they might be expected to produce transient response featuring a "double decay" sound profile. The phenomenon has been well documented and studied in the context of the piano but has not been systematically studied for other instruments. The results show considerable variation among instruments. The piano is indeed predicted to show double decays over most of its range. In the tested guitar, by contrast, double decays are likely to be confined to a few notes near strong body resonances. Other instruments fall between these extremes. The lute and the mandolin, both normally strung with double strings, should both exhibit double decays over much of their playing range, especially towards the higher end. The banjo is single-strung but is also predicted to show strong double decays, especially for higher notes in its range.

Electric-to-acoustic pickup processing for string instruments: An experimental study of the guitar with a hexaphonic pickup

A signal processing method to impart the response of an acoustic string instrument to an electric instrument that includes frequency-dependent string decay alterations is proposed. This type of processing is relevant when trying to make a less resonant instrument, such as an electric guitar, sound similar to a more resonant instrument, such as acoustic guitar. Unlike previous methods which typically only perform equalization, our method includes detailed physics-based string damping changes by using a time-varying filter which adds frequency-dependent exponential damping. Efficient digital filters are fit to bridge admittance measurements of an acoustic instrument and used to create equalization filters as well as damping correction filters. The damping correction filters are designed to work in real-time as they are triggered by onset and pitch detection of the signal measured through an under-saddle pickup to determine the intensity of the damping. A test case is presented in which an electric guitar is processed to model a measured acoustic guitar.

Perceptual evaluation of bracewood and soundboard wood variations on the preference of a steel-string acoustic guitar

The wood of the spruce tree (Picea spp.) has been valued for centuries as an ideal soundboard for stringed instruments due to its material acoustic properties. There is large variability in these properties between individual trees of the same species and even within an individual log. It stands to reason that this variability would produce audible differences in the sound quality of otherwise identical musical instruments. Furthermore, there may be a suite of physical characteristics of the soundboard that would result in optimal sound quality for a given design. Nine steel-string guitars of the same model were produced. The guitars varied only in two parameters: the density and Young's modulus of the soundboard and bracewood. This variability was representative of the range of wood currently produced by Pacific Rim Tonewoods. A short music sequence was used for a pairwise preference evaluation in a listening test. The results suggested that, for this particular model (the Taylor 814ce Grand Auditorium), the low density and Young's modulus of the soundboard and bracewood had a positive impact on the sound quality. More generally, these results underscore the importance of integrating a given design with the physical characteristics of the component wood.

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.

Active control and sound synthesis--two different ways to investigate the influence of the modal parameters of a guitar on its sound

The vibrational behavior of musical instruments is usually studied using physical modeling and simulations. Recently, active control has proven its efficiency to experimentally modify the dynamical behavior of musical instruments. This approach could also be used as an experimental tool to systematically study fine physical phenomena. This paper proposes to use modal active control as an alternative to sound simulation to study the complex case of the coupling between classical guitar strings and soundboard. A comparison between modal active control and sound simulation investigates the advantages, the drawbacks, and the limits of these two approaches.

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.