Distinctive in shape, size, construction and playing position, the Burmese harp has been traditionally tuned by ear; that is, without the intervention of a monochord or more recent devices, such as electronic tuners. In the latter regard, it is similar to harps and lyres of Antiquity: in Mesopotamia about four millennia ago, Ancient Greece more than 2300 years ago, and Ancient India about 1700 years ago. Also of plausible relevance to Burmese harp tuning are tunings of fixed-frequency instruments of other Southeast Asian traditions: of Central Java and Thailand, for example. Although such xylophones and metallophones have also been tuned by ear and employed in Burmese classical music along with the harp, the inharmonic spectra of their tones differ from the harmonic spectra produced by the open strings of the harps and lyres just mentioned. In particular, open strings produce predictable beats when plucked simultaneously.