My thoughts on Jawari: (refined)
The Jawari is a unique feature to the instruments used in Indian classical music. It is rarely found in other systems of music. Its literary meaning is somewhere around ‘life’, i.e. here giving life to the musical note.
Being a physician with very strong science base, mind does not digest the mystic facts from old literature (mostly the subjective translations) or from orthodox musicians. There can be flaws at various steps of inheriting the knowledge. The things should be thought, tested & verified on the basis of available science laws as far as possible.
Jawari, though a small looking matter involves multiple branches of knowledge like Music, Physics, Physiology, Psychology & so on. Anybody having one of these components missing can end up with untoward result in understanding or explaining.
Let us first try to understand on the basis of physics:-
Jawari is produced from the flat bridge which is different from all other types of bridges i.e. unlike the one used in mandolin with very sharp point of rest for the string on it. All the instruments like Tanpura, Veena, Sitar, Sarangi, Sarod, Dilruba & few others with sympathetic strings use Jawari bridge in one or the other form.
Here a small apparent slope is given on the Jawari bridge from the point of contact of string towards it’s another end. It is very precise work & needs high expertise for making it. After giving adequate slope, a small thread is passed between the string & bridge. The thread is adjusted along the string length in contact with bridge to make the emerging sound the most charming. To make the Jawari effective the slope & position of thread needs to be changed in relation to the string (length, diameter & tension, i.e. pitch desired) and the force of plucking.
Now what difference is made to the sound by making such arrangement? Let us see.
As everybody knows when a string fixed at two points is plucked it gives a ‘wave’ pattern. Two points where string is fixed, are called nodes; height of wave made by moving string being maximum in the centre part i.e. amplitude, the point being called antinode; two distinct boundaries of the wave, upward curve & downward curve.
In simple bridge two nodes have fixed position in any cycle of the wave formation. While in Jawari bridge, one node (non- Jawari end of the string, i.e. upper end in tanpura) is fixed but node at Jawari end can be made variable by changing the thread position. This variability in the node position is not only operative for different pluckings, i.e. in different thread settings; but also applies for a single plucking i.e. in a single thread setting How? Here is the answer.
In a single stroke, with the fading of the sound wave, the amplitude gradually decreases, so in a slope of bridge, the striking point (the point of actual contact of string over the surface of the Jawari bridge) also changes proportionately. Initially at the onset of wave, the amplitude is maximum, so it strikes the deepest part of the slope (effective length = length of the string between two apparent nodes – length between point of contact with flat bridge while playing & point of contact with flat bridge at rest). As the sound fades, its amplitude decreases, so smaller waveform will be striking more ‘near’ to the crude (static) node on the Jawari bridge (as it is shallower). As the sound fades the effective length increases from the shallowest point of contact on bridge up to the point of contact at rest. It continuously changes the length giving an effect of emerging & submerging the resultant sound
As it is well known that pitch of sound generated by plucking the string is dependant on various factors like length of string, tension in the string, diameter of string etc. This means that (keeping other variable factors same) with the changing effective length, the pitch also should get changed & things should turn ‘unmusical’. Very logical, but wait, some other factors are also coming into the play.
Apparently, wave generated from the string (standing wave as it is known as) has two components, upward & downward (remember this is very limited two dimensional vision otherwise it can be 3D phenomenon having vectors in 360 degrees). Vibrating string strikes Jawari bridge only during downward curve while it does not touch it in upward curve. This means Jawari effect is manifest only for the downward component of the wave while upward component is unaffected by Jawari . So, approximately around 50% component of the wave has fixed pitch while rest 50% has variable pitch. (Again if we think 3-dimensionally the Jawari component of the wave will be much less than 50%). So the major component of the pitch in a single pluck is fixed & only part is variable, The variable component is too fast & too small to be perceived by our auditory system as individual frequencies in a short time (this can be compared with the cinematography that different fixed picture frames if moved at some speed gives our brain an illusion as if it is live & moving, though nothing in fact is moving). Here the limitation of our nervous system (to analyze abundant signals in a very short time) is made use to our advantage.
So, the Jawari imparts major component of fixed node & minor component of shifting node, the resultant effect being a fixed pitch note with somewhat sustained emerging/fading wave of music giving it a live effect in a single pluck. This ‘wavy’ effect is due to inability of our Nervous system to process excessive signals in a short span of time, though the sounds of varying range of individual pitches do exist as a minor component in addition to major component of fixed pitch. Another effect is gain in the volume of sound by striking against the bridge surface
The above description applies mainly to Tanpura & somewhat to Veena and Sitar. The main bridges in Sarangi, Dilruba, Sarod are sharp but their sympathetic strings use small Jawari bridges (2, 1, 1 respectively) to get sweet sustained tone.
The physics of Jawari with thread is still more complicated than it seems. Effect of passing thread is giving many other questions. Is it a convenient alternative to perfect Jawari making for a particular pitch? It needs much deeper thought.
To be continued in future… along with other issues like ‘variable shadaj’.
