It was at the curiously titled talk Archaeology Of Listening Practices In Theatre, organized by the India Foundation for the Arts, or IFA, in Bengaluru last October, where I first came across Umashankar Manthravadi. At 75, he has been credited with several inventions in sound technology, the latest being the ambisonic tetrahedral microphone series called Brahma. It is a rare and uniquely designed microphone, with four heads which capture all the properties of audio.

With each innovation, he has extended the study of archaeoacoustics (the archaeology of listening) in India. Before interacting with Manthravadi, I had always thought of archaeology as a visual medium, where tangible objects narrate the history of a site. But here was a discipline that enabled an understanding of ancient performance spaces through their sound properties.

The Brahma series of microphones.
The Brahma series of microphones.

Archaeoacoustics is a relatively new field of archaeology, which gained prominence in the 1990s and early 2000s, when some serious work began to appear across the world, such as the study of prehistoric painted caves of France and the exploration of Stonehenge’s acoustics by scholars of Huddersfield and Salford Universities. Instead of basing conservation efforts merely on visual architecture, geological processes and chemical compositions, one could now expand one’s understanding of a site based on its sound properties. “It tells us how people were listening and performing in an age of no industrial noise. Also, it changes the way you would conserve a space," says Arundhati Ghosh, executive director, IFA, which gave Manthravadi a grant to aurally map two ancient performance sites—Nagarjunakonda in Andhra Pradesh and the Vadakkunnathan Temple in Kerala. “If the performance space is located within a rock-cut cave, its sonic property revolves around sound bouncing off the stone. But if you paint over it, in the name of conservation, that property is lost."

Even though the field is nearly two decades old, Manthravadi remains a flag bearer of sorts for archaeoacoustics in India. While he started his work in the 1990s, when no one had even heard of the field, one has seen some more professionals from related disciplines join in the past three-four years. For instance, in 2014, tech geeks Akash Sharma and Snehal Thomas Jacob started Sound Codes, a sound research lab in Mumbai that catalogues the acoustic signatures of heritage structures across India, from temple cave complexes to colonial theatres, besides providing sound consultancy to artists, producers, and more.

Together with the tetrahedral microphone and multiple-channel digital recorders, a low-cost kit (the Brahma) was ready for archaeoacoustic explorations

It’s surprising to note, though, that Manthravadi is not trained in this discipline. A sound recordist and technician by profession, he helped set up and maintain the Archives and Research Centre for Ethnomusicology in Gurugram. Manthravadi had not considered the acoustic properties of a space until he was requested by a friend, Cecil Thomas Ault, former professor of theatre history at Indiana University of Pennsylvania, to examine a site in Odisha. Manthravadi—his interest piqued—had to determine whether the site was a theatre built according to the rules of the Natya Shastra.

The site turned out to be Rani Gumpha, a double-storeyed monastery from the third century BC, carved out from a hill, in the Udayagiri cave complex. A visit in 1994-95 to the ancient cave turned into a life-changing moment for him. “The minute you step off the stone path into the amphitheatre, there is a large amount of amplification of the voice. Even a whisper is perfectly audible to the audience. But the minute you step off the stage, the sound is as normal as it would be in any open space," he says.

It made him think about the architectural elements that had created this effect. Manthravadi spent a week measuring every element of the structure, and then a year building the computer model. This revealed the contribution of the rear walls and curved floors to the overall sound design of the site. He experienced a similar sensation when he recently visited Anupu, in the Nagarjunakonda area, to measure the ambisonics at a fourth-century AD site, built in the Graeco-Roman style of amphitheatres. Located on the banks of the Krishna, the site retains just the brick core of a structure, which probably was once sheathed in stone. The strong, clean reverberations struck him as soon as he entered the space.

The only difference between the first visit to Rani Gumpha and the latest one to Anupu is the kind of gadgets that Manthravadi now has in his arsenal. When he started out, equipment was huge and hard to transport. During one visit, he had to carry a large full-frame computer to Rani Gumpha, connect it to overhead wires, only to find out a couple of hours later that he had run out of recording space. Today, there are 8 to 10-channel recorders that have plenty of memory.

However, what worked to Manthravadi’s advantage was that he was well-versed with the theory behind these gadgets. And, with their patents having expired, Manthravadi decided to make his own low-cost, battery-powered loudspeaker, capable of 200 watts of audio power. He was still struggling to make tetrahedral arrays (the arrangement of microphone capsules), when a low-cost recorder, Zoom H2, was released, which Manthravadi modified to suit his microphones.

Around 1998, he began to correspond with Prof. Angelo Farina, from the University of Parma, who had been conducting such measurements in 13th century performance spaces in northern Italy. “I sent him my prototype and he asked me to build 10 of these. He also asked me to think of a name for it, and I came up with Brahma, for its four heads," he says.

Together with the tetrahedral microphone and multiple-channel digital recorders, a low-cost kit was prepared for archaeoacoustic explorations. The Brahma microphone has gone through several iterations. Until October 2016, it was manufactured at a small factory in Noida, near Delhi, with several hundreds being sold. Now, he plans to make them at home in Bengaluru. “Prof Farina has also helped me with software to interpret my recordings with," he says. Armed with this equipment, Manthravadi now plans to take ambisonic measurements of Hampi in Karnataka and Kanheri, within the Sanjay Gandhi National Park in Mumbai, and revisit the Rani Gumpha complex.

So, how does it work? Usually, Manthravadi plays a sound piece at the site, which starts at an inverse sine sweep—beginning with the lowest frequencies and going up to the highest. He places an omnidirectional speaker and records the impulses with the ambisonic microphone. The software then converts these into impulse responses—each containing the necessary values of reverberation, frequency, and more. Using these values, Manthravadi now plans to create a website, on which it would be possible to recreate sounds as heard at those sites in their original state. Ghosh says about the website, “It could be a song I am humming right now. If I go to the website and choose Guruvayoor Temple, then I will get to hear that song exactly the way it would have sounded back then". Manthravadi is looking for funding to set up the website.

I ask him if the awareness about archaeoacoustics has changed at all in India, and he shares an anecdote. Manthravadi got an unusually warm reception at the Archaeological Survey of India (ASI) office in Hyderabad, when he went there last year to get permission to study Anupu. “The officials wanted me to take measurements at Golconda as well. There is a place there, where you clap and you can hear that sound inside the fort. As a result of some restoration work, the sound of the clap can’t be heard any longer. The fact that the ASI is beginning to even recognize accidental acoustic damage, as a result of restoration, in itself is heartening," he says.

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