Dupki, Dhap, Duff,Bairagan is a drum, found in many parts of the world,
and is particularly used in Bangladesh/ West Bengal & Indian folk music (Baul, Fakiri).
It is similar to the Western tambourine, it consists of a circular frame made of the wood,
between 7 and 9 inches in width and 2 to 4 inches in depth.
It is covered on one side with a Drumhead made of goat skin,
while the other side is left open. It is normally played with the palm and fingers
of the right hand, while the left hand supports the drum.
The fingertips of the left hand can be used to bend the pitch by
applying pressure near the outer rim. Normally, without,
it has a very high pitched sound. To get a good bass sound,
the performer reduces the tension of the Drumhead by sprinkling
water on the inside of the instrument. This process may have to be
repeated during a concert to maintain a good sound. However,
if the instrument is too moist, it will have a dead tone,
requiring 5-10 minutes to dry. Tone is also affected by external
temperature and moisture conditions.