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International audience; This paper is an attempt to solve two problems related to musical acoustics. The first one consists in defining a signature of an instrument, namely, summarizing its vibroacoustical behavior. The second one deals with the existing relationship between the musical sound and the vibroacoustic properties of the instrument body. The violin is the application of this paper. A proposed solution for the first problem consists in an estimation of the bridge transfer mobility and the mean-value of the lateral bridge transfer mobility. The second problem is studied via the comparison between the amplitudes of harmonics, extracted from a glissando audio signal, and the lateral bridge transfer mobility: Both curves exhibit similar features. This is the main result of the paper. This is evidenced by studying the effect of a violin mute on both the lateral bridge transfer mobility and the produced sound. Finally, this is evidenced by successfully identifying which violin is played in an audio recording, using the computation of the Pearson distance between the distribution of the amplitude of harmonics and a database of measured mobilities.

International audience; This paper focuses on the bridge mobility of violins. The mobility, or mechanical admittance, quantifies the efficiency of the instrument body to vibrate when a force is applied to the structure. The computation of the mean mobility, after the Skudrzyk's mean-value theorem, enables a global characterization of the bridge mobility. The choices made by the luthier, when he builds, restores, or adjusts an instrument, modify the mobility and the mean mobility: this is the signature of the instrument. This study shows that the bridge mobility measurement may be helpful for luthiers to objectively characterize an instrument. Two experimental applications on the violin are presented in the paper: the first one studies the characterization of the same violin in several configurations, corresponding to different positions of the soundpost. The second application studies the effect of a violin mute on both the bridge mobility and the spectral characteristics of the produced sound. This study is a part of the PAFI project, which aims to develop a set of tools dedicated to instrument makers.

International audience; The differences of assessment between musical instruments of the same kind (e.g classical guitars) covers aspects linked to sounds, expressibility, or even manufacturing process. How to extract relevant information related to these aspects by measuring well chosen physical (acoustical, vibratory) parameters ? The aim of the proposed study is to identify criteria enabling the clustering of string instruments in different classes. The plucked instruments will be our application. The knowledge of these parameters would then allow to give an help to the instrument maker in the adjustments and settings likely to be made on an instrument. The modal parameters (frequency, and damping coefficient) can be estimated accurately on a large frequency range from impulse responses by using the high-resolution ESPRIT method, associated with the ESTER criterion to enumerate the signal components. Global parameters, such as the modal density, loss factors and modal overlap factor can be determined and used to estimate average mobility, derived from Skudrzyk's mean-value theorem. The application on guitars and ukulele shows a common behavior of their average mobility: it remains constant in the mid and high frequency domains. The corresponding value is used as one of the parameters enabling the % clustering and the characterization.