On the dynamics of the clavichord
Christophe d’Alessandro · The Journal of the Acoustical Society of America · 2008
The clavichord is generally considered as the most sensitive and subtle among keyboard instruments. The player/instrument interaction is very direct: the mechanism is reduced to as simple lever, allowing for a direct contact between the finger and string through the key. Key velocity, two string-tangent contact signals, radiated acoustic signal have been synchronously measured for about 10 dynamic nuances and all the notes of four instruments (a 51 notes unfretted instrument, after a German XVIIIth century model, a 51 notes fretted instrument after Hubert (1754), a 45 notes fretted instrument, after a German XVIIth century model, a 37 notes fretted instrument after a medieval model). The instruments can be portrayed in terms of dynamic range, tonal/spectral colour and sound decay time. As for the dynamics, there is some evidence for a linear relationship between sound pressure level and the velocity of the tangent; and an almost constant spectral richness independently of loudness (in contrast with e.g. the piano). A simple model of the tangent/string interaction is proposed. This model reproduces well the behaviour of experimental data, and it may explain why sound quality of the clavichord depends much on the player's ability.