Research projects of

Erik V. Jansson 
Earlier a wide covering field was investigated ”Physics of the Violin. Properties of the complete system as function of its parts”.
The investigations were made in cooperation with Nils-Erik Molin at Luleå University of Technology (holografic measurments of vibrations), Benedykt Niewczyk, fourth generation violin maker (making of experimental violins) and Lars Frydén, expert violin player (test playings). A new way to record violin properties have been developed and in cooperation with the Järnåker Foundation properties of soloist violins (Stradivarius, Guarnerius, Guadagnini, etc) have been recorded
and limited the field of investigations. Presently properties found, a dominating ”BH-hill,” is being investigated as well as a dominating resonance at approximately 550 Hz. Computer analysis of the violin function has been recently been started in cooperation with Peter Carlsson and Mats Tinnsten at Mid Sweden University.
 

Violin tone, time history with
possibilities to listen to initial,                         from CD-ROM picture with sound
middle and late part prolonged                       skojigt ljud

TV-hologram (Saldner, Molin and Jansson) 
showing operating deflection shape as function          from CD-ROM moving picture with sound
of frequency with driving signal                                  skojig rörlig bild
audible.

Erik Jansson: current project:
The long term project has been ”Physics of the violin”. Properties of the complete system as function of its parts has been supported by NFR and KTH. An electro-acoustical method to measure bridge mobility was developed. In cooperation with B Niewczyk a fourth generation Polish violin maker non-destructive methods to perturb violin properties was developed with support from the Swedish Institute and the Wenner-Gren Foundations for Scientific Research. Playing qualities of the experimental violins were tested in co-operation with professor Lars Frydén as expert violin player. Soloist quality violins have been tested in coopertion with the Jaernaaker foundation, Dr J Huber. Non-contact vibration measurements using holographical methods  were made together with professor N-E Molin at Luleå University of Technology.

During the experiments it has become clear that a property in the 2.5 kHz range is most important for the quality. This property labelled initially the Bridge Hill as the violin bridge has its first in-plane resonance in this range and the response peak was expected to be the main parameter of this peak. Experiments have proved this expectation to be wrong. The hill remain for bridges without in-plane resonances in this range and that the properties of two violins remains independent of bridge. Old violins have shown a less peaked hill most likely stemming from ageing of the wood. The thickness of the top plate and the cross-stiffness of the top plate wood are other important parameters. Experiments proceed to verify the hypothesis of the BH-hill properties. The project is supported by Carl Trygger Foundation.
 

Two doctor students, Knut Guettler and Tarmo Pajusaar. 
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TMH - Department of Speech, Music and Hearing
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Updated 02.04.17 Maintained by: erik@speech.kth.se