Ask a new student what śruti is and you will usually be told it is the key — the note the song starts on. That answer is not wrong so much as inert. It describes a pitch. Śruti is a relationship.
The drone is not accompaniment
A tambura plays no melody, changes nothing, and goes on doing so for as long as you sing. It is easy to treat it as atmosphere. But every swara in Carnatic music is defined against it: sa is not a frequency, it is agreement with the drone, and ri, ga, ma and the rest are not fixed points but positions held in tension with a sound that never stops sounding.
This is why a student who practises to a keyboard and a student who practises to a tambura end up with different ears. The keyboard tells you where the note is. The tambura asks you, continuously, whether you are still there.
What "in śruti" actually means
Being in śruti is not a state you arrive at and keep. It is a correction you make several times a second, mostly below conscious attention, the way you stay upright. This is why it can be lost by fatigue, by a cold, by singing at the top of the range, by nerves — and why it comes back with rest rather than with effort.
It is also why the traditional first exercise is not a song. It is a long-held sa. Not because holding one note is musically interesting, but because it is the only exercise in which nothing else can distract you from whether the relationship is intact.
नादतनुमनिशं शङ्करं नमामि मे मनसा शिरसा ॥
nāda-tanum aniśaṃ śaṅkaraṃ namāmi me manasā śirasā
I bow, with mind and with head, to Śaṅkara whose very body is sound. — Tyāgarāja
A practical suggestion
Give the first ten minutes of practice to the drone alone. Sit with it before singing anything. Sing sa, hold it until the breath runs out, and listen for the moment when your voice and the drone stop being two sounds. Then begin the day's exercises.
Students who do this for a month rarely go back. The exercises do not get easier — but they start being about something.
Written by Yogashree MV — Sanskrit scholar, yoga philosopher and Carnatic vocalist. More about her work, or send a question on WhatsApp.