The guru-shishya (master-student) parampara is central to the evolution of Carnatic music. Although compositions have been notated and codified to an extent, there is ample scope for improvisation and extempore for a performing artist. This could be through manOdhaRma - like rAga Alapana and swara singing. Even rAgas are always open to interpretation. The consequence of all this has been the system of "schools of music". We refer to them as bANi. This is similar to "gharanas" in Hindustani music.
Veena, being a complex instrument, has varied styles of playing. This variety includes:
How frequent meettu (i.e. plucking of string) is done
Importance given to sAhithya
gamakas (pulling of strings between the frets)
Adherence to tradition
Strength of meettu
Unlike vocal music, bANis in veeNa are heavily influenced by geography. The bANis may be broadly categorized as:
Tanjore bANi: Tanjore (Thanjavur) had always been the seat of carnatic music, considering that the trinity lived here. The Tanjore quartet (the four brothers who lived here in the 18th century, and said to have learnt from the trinity) were also excellent vaiNikas. veeNa dhanammal, the grand old lady of carnatic music belongs to the parampara of the quartet. Needless to say, the tanjore bANi holds the enviable position of being the oldest and hence the most authoritative system of playing the veeNa. There is a thrust on usage of gamakas and less emphasis on rhythmic acrobatics. meettus are used as sparingly as possible. When used, meettus closely follow the lyrics of the composition - and hence carry the true spirit of the composition. Brinda/mukta (grand-daughters of dhanammal), kalpagam swaminathan and vidUshi padmavathy exemplify this style of playing.
KaraikuDi bANi: I wasn't quite aware of this bANi, until I came across a mesmerizing concert of vidUshi rajeswari padmanabhan on youtube. She is a descendant of the karaikuDi veeNa brothers. The tonal quality of the karaikuDi veeNa is superlative - it is manufactured somewhat differently from the tanjore veeNa. Although there are many similarities with the tanjore style of playing, karaikuDi bANi is characterized by strong meettus and grip over laya. The tALa strings are strummed religiously, on every tALa beat.
Mysore bANi: Thinking of veeNa and mysore - what springs to my mind is sangeetha kalAnidhi Doraisamy Iyengar. The mysore bANi lays more emphasis on swaras and hence many more occurrences of meettu than the other bANis. Vidwans and vidushis following the mysore tradition revel in racy passages: the split-fingering mechanism is a hallmark of this bANi. It involves placing the forefinger and middle-finger on adjacent frets and using the latter also for a meettu (in addition to meettus done by the right hand). Sahithya is generally not honoured by vaiNikas of this bANi. Gamakas are employed sparingly.
Kerala bANi: Sangeetha kalAnidhi K.S.Narayanaswamy is an exponent of this bANi. The style is very similar to tanjore, but with influences from mysore when it comes to tAnam playing. Other artists following this bANi include Trivandrum R.Venkataraman and to a lesser extent, Anantapadmanabhan.
Andhra bANi: Although this bANi also uses the split-fingering technique of the mysore school, gamakas assume an important place. Sahithya is not as religiously followed as the tanjore bANi; nor are the meettus as reckless as the Mysore bANi. Considering the styles of EmaNi sankara sastry and his illustrious student chiTTi bAbu, I would say that the andhra style places lot of emphasis on aesthetics. There is a lot of rapture, and less of rigidity. tALa strings are strummed frequently, even during rAga AlApana.
(Secret bANi) or Balachander bANi: This is probably the only bANi that is not driven by geography, but by pure intellect. S.Balachander evolved his own style of playing, making it as gAyaki (i.e. close to vocal music) as possible. It involves pulling the string between frets to achieve higher notes. For eg;- by placing the fingers in the 'gA' fret, and pulling the string progressively - he achieves mA, pA, dhA, etc. This is a radical technique, and ought to be carefully executed - if not, plenty of apashruthis (off-notes) may be heard. Many vaiNikas, regardless of affiliations, have emulated his style. Vidushi Jayanthi Kumaresh, although trained in the Tanjore style, considers Balachander as her "mAnasika guru". Trivandrum Anantapadmanabhan is another vaiNika who appears to have been influenced by the Balachander-style of playing. It still remains a mystery as to why Balachander was not awarded the Sangeetha Kalanidhi (the Nobel prize equivalent for Carnatic music): it could be because of his extremist views on Swati Tirunal, which could have irritated Semmangudi and the like.