In 1995 I was asked to acoustically analyse recordings of a nearly unknown lithophone from a small village in West-Sumatra. The talempong batu consists of six large stones of unknown grey to beige material, which look quite rough and natural and are approximately 100 to 150 cm long, 30 to 40 cm wide and 15 to 25 cm thick. All six stones show a complex spectrum with inharmonic overtones that is typical of vibrating 3D objects. The interval matrix between the lowest partials of all six stones was determined. The analysis of the tuning system showed quite unexpected results: the
four lowest stones establish a complex system of intervals, which perfectly matches some intervals that are known as perfect major third (5/4, 386.31 cent), ‘Pythagorean’ ditone (81/64, 407.82 cent), and syntonic comma (81/80, 21.51 cent). The deviation between these theoretical intervals and the measured intervals from the instrument is less than the just-noticeable pitch difference (JND) that the human ear can detect. If it is assumed that this system did not simply evolve by chance, its existence allows us to draw some important conclusions on the cultural background and capabilities
of its creators.