What are the 22 Shruthis in Carnatic Music? Overview Guide

What are Shruthis?

The word Shruthi is used in many contexts. 

1. Aadhara Shruthi is also very commonly referred to as just Shruthi. You can read the blog –What is Aadhara Shruthi? to know more about the same. 
2. In another context, Shruthi refers to the smallest perceived interval of pitch. Not every frequency (Hz) is noticeably different to human ears or more importantly, musically necessary or significant. So, in Carnatic music, the smallest perceptible pitch intervals in reference to any particular Aadhara Shruthi are called Shruthis. There are 22 Shruthis.

Modern Carnatic performance operates within the 12 Swarasthanas. The 22 Shruthi model belongs primarily to historical and theoretical discussions.

22 Shruthi system

To understand the 22 Shruthi system, knowing the 7 notes (Sapthaswaras), 12 pitch positions (Swarasthānās) are necessary. You can know more about 7 Notes, 12 Swarasthānās here. 

After we know the 12 Swarasthānās, here is how we can understand the 22 Shruthi system.

There are two models here:

1. A modern conceptual understanding. By using a long string instrument, one can observe that each Vikruthi Swarasthana appears to have two points. A starting, and an ending point. Each Vikruthi Swarasthana can be thought of as having a lower and upper microtonal boundary. We know that out of 12 Swarasthānās, Sa and Pa are prakruthi swaras, so the remaining 10 Swarasthānās will have two points each. That is, for example, R1 itself will now have two possibilites. Can be imagined as R11 and R12. Similarly for R2, G2, G3, etc. In total, the Swarasthānās of Vikruthi swaras itself will give 20 possibilities. Now, including Sa and Pa in the octave, this will be totaling as what we call the 22 Shruthi system. This is only a conceptual explanation to help understand how the number 22 can be visualised.
2. Ancient Original Historical 22 Shruthi Theory. Historically, however, ancient musicologists described the 22 Shruthi system differently. In this model, the Shruthis were unevenly distributed among swaras like so:
   • Sa – 4
   • Ri – 3
   • Ga – 2
   • Ma – 4
   • Pa – 4
   • Da – 3
   • Ni – 2
   • These numbers represent shruthi spans between swaras, not multiple discrete notes assigned to each swara. And also, these 22 Shruthis were not treated as 22 independent performance notes in modern Carnatic practice.

Over time, Carnatic music pedagogy evolved toward the 12 Swarasthana system used in practice today, while the 22 Shruthi model remained part of historical theoretical discussion.