Erik V. Jansson

On Vibration Sensation and Finger Touch in Stringed Instrument Playing

The vibration levels in four traditional stringed instruments during playing have been investigated, including the double bass, violin, guitar, and the piano. The vibration levels, which were measured at several positions and at different dynamic levels, were evaluated with respect to reported thresholds for detection of vibrotactile stimuli. The results show that the vibration levels are well above threshold for almost all positions on the instruments in normal playing. It is concluded that the perceived vibrations may be of some assistance with regard to intonation in ensemble playing, in particular for the bass instruments. The finger forces exerted when playing the bowed strings, as well as the touch forces in piano playing were studied briefly. It was concluded that the kinesthetic forces perceived in playing may assist the timing in performance.

From touch to string vibrations. I: Timing in the grand piano action

This article describes an experimental study of the timing in the grand piano action. The function of the action is described by timetables for the motions of the moving parts. Important timing properties included are the relation between key bottom contact and hammer–string contact, the interval of free hammer motion before the impact on the string, and the hammer–string contact duration. The influence of the regulation and dynamic level on these timing properties is analyzed. The results of the measurements are discussed, with a focus on the implications for piano playing, regulation, and design.

From touch to string vibrations. II: The motion of the key and hammer

This article describes an experimental study of the motion of the grand piano key and hammer. The motions were registered by means of an optical position measuring system. The measurements include typical key and hammer motions at different dynamic levels and for different types of ‘‘touch.’’ Also, the accelerating force on the hammer before release (‘‘let‐off’’), and the following free motion of the hammer were investigated. Resonances in the hammer were detected and examined by modal analysis. A possible influence of the pianist’s touch on the string vibrations via the hammer resonances is discussed.

From touch to string vibrations. III: String motion and spectra

This article describes an experimental study of the wave motion on the piano string and the corresponding spectra. The string motion was detected using an electrodynamic method. The measurements include typical initial string waveforms and spectra in the bass, mid, and treble at three dynamic levels (p–mf–f ). The interaction between hammer and string is also analyzed, including multiple contacts in the bass. The influence of hammer properties is investigated by shifting hammers and adjusting stiffness (‘‘voicing’’). A comparison between the string and bridge vibrations is presented, including the influence of the resonant tail lengths of the string (‘‘duplex scale’’). A brief account of the interaction between damper and string closes the study.

Parameters of violin plates and their influence on the plate modes

Noncontact measuring methods and numerical calculations are used in a study of musical instruments. First, a simple method to determine the material parameters of a blank to a violin plate is prese ...

Vibration modes of the violin forced via the bridge and action of the soundpost

The action of the soundpost in a violin is not well understood and fundamental knowledge is needed. Therefore low‐frequency forced modes, operating deflection shapes, 250–600 Hz of a violin were investigated. Harmonic, sine wave, excitation was applied via the bridge (resembling playing) or via the sound from a loudspeaker. The latter excitation gives a reciprocal measure of radiativity. The modes were investigated with TV‐holography and electro‐acoustical admittance measurements. A carefully selected violin was investigated without soundpost, with soundpost, and with the soundpost position shifted toward the centerline. Answers were sought to three questions: Which are the violin modes forced via the bridge? To what extent do they radiate sound? What is the action of the soundpost? The observed modes were mostly not pure normal modes but mode combinations. Generally there is a nodal line close to the soundpost position of the plates. Schelleng has hypothesized that the main action of the soundpost is to ...

On eigenmodes of the violin—Electronic holography and admittance measurements

The present experimental investigation, using recently assembled advanced electro‐optical equipment for vibration analysis of three violins, was conducted to seek answers to three questions. A general or global question: Which parts of the violin body are vibrating the most? And two questions related to tonal quality: Are basic low‐frequency vibration modes of a musically superior instrument different from those of an inferior violin? Can some special vibration properties be found to support the ‘‘bridge hill?’’ Optically obtained vibration modes were recorded as well as frequency responses in the form of admittance measurements. The investigation showed that the vibration modes found earlier are representative both for the inferior violin and the musically superior instruments, although discrepancies can be seen, both in eigenmode shapes and admittance responses. The experimental results are also in quite good agreement with published results of the modal analysis of a violin. Further, the experimental r...

Transient wave response of the violin body

In this investigation, the dispersive, transient wave propagation field of a complete violin excited by a mechanically induced impulse at the top of the bridge is presented. By means of double pulsed holographic interferometry with a ruby laser as light source the propagating wave field is recorded. From presented interferograms, it is seen that initially the top plate acts mainly as a nonsymmetric dipole with centers at the two bridge feet. The back plate is strongly coupled to the motion of the top plate by the sound post and acts more like a monopole. Thus the position of the sound post is crucial to the performance of the instrument. The free edges at the f‐holes are very early reached by the dispersive bending waves of high amplitude probably giving a significant contribution to the sound of the violin family instruments.

Physics of the violin

A method to measure acoustical properties of the violin has been developed. The bridge is excited by an impulse force hammer (see www.speech.kth.se/music/acviguit4). Bridge vibrations are recorded by a small magnet and an electrical coil. Measurements can be made in an ordinary room and give a record of properties built into the violin body. An old good Polish violin, B Dankwart, Vilnius ca. 1600 shows typical results with peaks P1, P2 and the BH‐hill. Our goal is as suggested by Gabriel Weinreich ‘‘to understand, not to copy,’’—Stradivarius. By shifting the soundpost position the peaks P1, P2 and BH can be somewhat monitored. It can be shown that the BH is not confined to the bridge only. The feet distance of the bridge is important but also the top plate. Marcin Groblicz, the great Polish violin maker, was court instrument maker in Krakow ca. 1600 to Sigismund, King of Poland and Sweden. I believe Gabriel Weinreich has some connection to Vilnius in Poland but unfortunately not to Sweden. We like Gabi.

Laser vibrometry measurements of vibration and sound fields of a bowed violin

Laser vibrometry measurements on a bowed violin are performed. A rotating disc apparatus, acting as a violin bow, is developed. It produces a continuous, long, repeatable, multi-frequency sound fro ...