I spent my afternoon today at Tablaphilia – a tabla symphony composed by Pt. Samir Chatterjee. It was incredible to listen to 22 drummers playing together on a single stage in harmony and conducted in a symphony. Do you find it strange when I talk about harmonics while describing something performed on drums? A lot of people new to Tabla certainly do. You could sense the confusion in the audience as they watched the band “tune” their drums. Most drums, such as the ones used in a rock performance produce only in-harmonic vibrations. You’d probably prefer a dry sound without any ‘ring’ on these drums contrary to what you get from a Tabla.
Tabla is part of a family of musical drums including Mridangam and Pakhawaj, which can produce harmonic overtones. In fact, tabla featured relatively much later in Indian music. There are several theories about its origins, such as the legend involving the famous musician – Amir Khusro  , and how he invented tabla when a jealous competitor broke his drum. Many also believe that Tabla may have more ancient roots in the instrument known as Tripushkara, which had three different parts like a drum kit: horizontal, vertical and embraced. I find this theory more convincing but the absolute beginnings of tabla remain unclear. However, we do know that Tabla became popular in the 17th century, when there was a need to have a drum that could give faster and complex rhythm structures required for the then emerging Sufi music style. The “finger and palm” technique used on the Tabla was much more suited for it than the heavier sounding Pakhawaj.
Alright, coming back to the central theme of the post: what allows a drum to produce harmonics? Without going into its mathematics (read, I can’t :D), allow me to refresh your memory about some concepts in harmonics. Perhaps you remember the experiments performed with the sound column and a tuning fork in your Physics lab.  You’d recall that a string vibrates at some fundamental frequency and its integer multiples are known as harmonics. Stringed instruments can vibrate in a harmonic series, and a unique combination of these harmonics make them sound the way they do. But what about a membrane such as the ones that used on these drums? Turns out that the drum-head on the pitch drum (the right one; See picture.) can also produce five such harmonics giving its musical effect. These are responsible for the different bols that are played on the tabla. There are two papers by the Nobel prize-winning physicist CV Raman, who has explored them in a lot of detail: "Musical drums with harmonic overtones" (C.V. Raman and S. Kumar, 1920) and "The Indian musical drums" (C.V. Raman, 1934)
Unlike most drums, tabla has a sophisticated mechanism to alter its pitch. All tablas are designed to have a pitch that can vary between a certain range. This is done by beating along the sides of the head and adjusting the tension in the straps on the side with wooden blocks. By carefully tuning several tablas, you can derive different notes used in music and have something as amazing like this:
It was exhilarating to hear the “notes” played by the drummers during the concert piece today as the tablas provided both rhythm and melody. As I was enjoying the music, I couldn’t help but wonder about the engineering skills and knowledge required to build these instruments. Most artisans responsible for building them have no formal training about the theory behind it. All the ingredients that go into making the drum, its shape, the three layers of membrane on the head and even the placement of the black spot (or syahi) contribute to the unique sounds of the instrument. Some of the techniques for building the drum have been passed within families over hundreds of years. The exact recipe for making the syahi, is still kept as a closely guarded secret in these families. This loading of the membrane with the syahi allows the tabla to produce overtones. Did you notice that it is placed off the center on the bass (the left drum) though? The membrane also has different regions which when struck in a certain manner produce the overtones. When you go about counting the different parameters and factors, it makes you wonder about how by mere experience, the makers of tabla could design it.
Listening to Tablaphilia was an incredibly unique experience. I always enjoy when students play together in a tabla class while learning a piece but having a complete performance like this was very new for me. Usually, tabla performances are either done solo or they give company to a melody instrument but never as an ensemble. Some connoisseurs of Indian music would argue that a format like this doesn’t offer any room for improvisations. Agreed; but then what is music without variety and experimentation. I look forward to more such symphonies and concerts.
- C.V. Raman (1934), The Indian musical drums. Available: http://www.ias.ac.in/jarch/proca/1/179-188.pdf.
- C.V. Raman and S. Kumar (1920), Musical drums with harmonic overtones. Available: http://www.nature.com/nature/journal/v104/n2620/abs/104500a0.html.