How many Shruthis are there in Indian Music?
तस्या दवविंश्शतिभेरद श्रवनात शृत्यो मता:।
हृदयभ्य्न्त रसंलग्ना नदयो द्वविर्शतिमर्ता :।।
This is an excerpt about Shruthi from Swaramela Kalanidhi, a 16th century text written in the Vijayanagara Empire by Ramamatya. It states that the heart centre has 22 nadis (channels of flow) and that each nadi emits a unique sound that can be perceived if one pays attention to it.
These 22 distinctions in the sounds emanating from the heart center are considered to be the 22 distinguished notes of naadh (sound).
What is Shruthi in Indian Classical Music?
लक्षे परोक्तसु पर्यातम संगीत्म्श्रुति लक्षणम ।।
Vishnu Narayan Bhatkande in his Abhinav Raag Manjari defines what is Shruthi in the above shloka. It states that: “A Shruthi is characterized as the sound usable in music that can be distinctly identified apart from other shruthis.”
Sa Re Ga Ma Pa Da Ni Ṡa are the notes in one octave, right? Scholars identify 22 Shruthis or micro-sounds in one such octave. They define Shruthi as the sound that can be clearly identified as different and distinct from the other sounds.
How are Shruthis distinguished?
Every sound that is around you has a frequency of vibration. We measure frequencies in Hertz (Hz). We need to understand about these frequencies to clearly get the concept of Shruthi.
Let us consider two frequencies: 256 Hz and 257 Hz. If we listen to them, they might sound similar but still have a difference, right? 256 Hz sounds more different from 512 Hz, as compared to 257 Hz.
Just as in a metric scale where there are several millimetres between centimetres, there are several frequencies in between 256 Hz and 257 Hz: 256.1 Hz, 256.2 Hz, 256.3 Hz and so on. There are several frequencies in between 256.1 and 256.2 also.
We can easily identify the difference between 6 cm and 7 cm with the help of a scale, maybe we can distinguish between 6.1 cm and 6.2 cms too. What about 6.1 cm and 6.15 cm? What about the difference between 6.005 cms and 6.006 cms? It is not easy right? As the space decreases, it gets harder to distinguish one measurement from the other. We can distinguish one length from another with a scale when they are a measurable degree apart.
Similarly, one can distinguish one frequency from another with ears when they are some Hertz apart. Even trained musicians may find it difficult to distinguish between a 240 Hz and 241 Hz, but if one moves from 240 Hz to 245 Hz, the difference can be clearly identified with human ears. One needs to understand this to understand what is Shruthi in Indian Classical Music.
Swar and Shruthi- the Classification:
चतुश्चतुश्चतुश्चतुश्चैव षडजम माध्यमपंचमा।।
द्वे द्वे निषाद गंधारो तरस्त्रिषभोधैवतो ।।
Each shruthi has a specific name, though there are variations in its ancient and modern usage.
The 22 Shruthi names in Indian Classical Music.