Mukhasangu (corruptly called morsangu or morsing) is a secondary percussion instrument played along with the mridangam in Carnatic concerts. . Identical to the Jew’s harp, it is an ancient instrument with a nasal, twangy sound. There were many players in Tamilnadu. Adichapuram Seetarama Iyer and Mannargedi Natesa Pillai achieved eminence by playing this harp skillfully to support Carnatic music.
This is a tiny instrument held in the left hand, the 'prongs' against the upper and lower front teeth. Some players hold the instrument between their teeth. It must make firm contact, but should not press too hard or you will give yourself toothache and potentially damage your teeth. Hold lightly but firmly.
Construction: The morsing consists of a 'tongue' of springy metal that is supported within a circular ring of iron which forms a frame. The 'tongue' is slightly curved at the free end and protrudes beyond the ring at the other end.
The is plucked with the Index finger of the right hand (backwards, not forwards) while the tone and timbre are adjusted by changing the shape of the mouth cavity and moving the tongue — kind of speaking silently, effectively. Further control of the sound can be achieved with the breath, but extensive use of this technique for fast, staccato effect quickly results in hyperventilation. Unusual for a percussion instrument, you can produce a very long duration note on the morsing by sucking air through it, sometimes (depending on the instrument) even without plucking it first.
Like the mridangam, the morsing is tuned to the tonic, which means you have to have one for each sruti. Fine tuning is achieved by placing small amounts of bee's wax on the end of the tongue.
Although a tiny and relatively quiet instrument, the morsing unmistakably adds to the music, reinforcing the sruti and providing a kind of textural as much as rhythmic accompaniment.