The acoustics of carved Baltic psaltery

The Baltic psaltery family of plucked string instruments includes the kantele (Finland), the kannel (Estonia), the kokle (Latvia), the kankles (Lithuania), and the wing-shaped gusli (Northwestern Russia). In its archaic, carved form, it has a limited range, 5–13 strings, usually tuned diatonically. By means of electronic TV holography, we studied the modes of vibration of several psalteries based on historic instruments. On the better instruments, the main body resonances are well distributed in frequency so that they support the various strings. Good string-to-soundbox coupling also appears to play a role. A useful method for studying string-to-soundbox coupling involves scanning at intervals as low as 0.1 Hz for narrow peaks within the nominal tuning range of the strings, and comparing them to their neighboring body resonances, while using electronic TV holography. Predictions of the Helmholtz resonance from sound-hole dimensions and air-cavity volume while neglecting damping in the sound holes yield upper limits when many small sound holes are involved. The locations of the sound holes, as well as their area, are found to have significant effects on sound quality and volume.