Modeling of the clavichord

One of the oldest musical instruments still in use, the clavichord has a beautiful but quiet sound. The sound production of the clavichord is based on a simple lever system, in which a metal plate called the tangent hits a pair of strings, when the player depresses a key on the keyboard. This principle is different from plucking of strings, as used in many of other string instruments such as the acoustic guitar, and also different from hammering the strings, another common way of exciting strings used for example in the piano. Nevertheless, we have created a computer synthesis method for clavichord tones using similar signal-processing techniques that we have used previously in the case of other string instruments. This shows that the waveguide string model and the principle of commuted synthesis are applicable to a wide range of stringed musical instruments.

The following table lists our clavichord-related research in inverse chronological order. For some publications, the PDF-file and a companion web-page containing sound examples are provided. These can be found in the leftmost column.

Publication Short description V. Välimäki, M. Laurson, and C. Erkut, "Commuted waveguide synthesis of the clavichord," Computer Music Journal, vol. 27, no. 1, pp. 71-82, Spring 2003. The commuted waveguide synthesis algorithm described in this long journal paper combines physical modeling and sampling: the string vibration is simulated with a waveguide model, but the soundbox response, the key-off noise, and the input signal for each string are samples. The waveguide string model is modified to allow the adjustment of the attack sharpness of tones (see page 75). Loop filter parameters of the string algorithm are approximated with simple polynomials as a function of the key number (see page 76). Finger vibrato is implemented by varying the delay-line length of the waveguide model. V. Välimäki, M. Laurson, C. Erkut, and T. Tolonen, "Model-based synthesis of the clavichord," in Proc. Int. Computer Music Conf. (ICMC'00), pp. 50-53, Berlin, Germany, Aug. 27 - Sept. 1, 2000. This paper reports our observations about clavichord tones and our first attempts to devise a waveguide synthesis model to imitate them. Two waveguide string models are used for each voice, because a pair of strings is associated with each key in the clavichord. Slight de-tuning of the two string models (i.e., a small difference in their delay-line length) brings about the beating of harmonics observed in recordings. The resonator bank model of the soundbox resonances explained in this paper was not used in a more advanced version of the clavichord synthesizer (see the CMJ paper above).