Shruti (music)

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For other uses, see Śruti (disambiguation).

The shruti or sruti (pronounced śruti) is a Sanskrit term, which in the context of Indian music, is considered the smallest interval of pitch that the human ear can detect.[1] It has been used in several contexts throughout the history of Indian music.

Contexts[edit]

To know the real meaning of shruti, it is important to know the various contexts in the history of Indian music where the term is used.[2]

Ancient period: Grama system[edit]

Bharata Muni uses shruti to mean the interval between two notes such that the difference between them is perceptible. He formulates jatis, which are classes of melodic structures. These can be further grouped into two gramasshadja-grama and madhyama-grama. The notes (svaras) are separated by intervals, which are measured in terms of shrutis.

The shadja-grama is given by the following division: Sa of four shrutis, Ri of three shrutis, Ga of two shrutis, Ma of four shrutis, Pa of four shrutis, Da of three shrutis and Ni of two shrutis. Bharata also describes an experiment to obtain the correct physical configuration of shruti in shadja grama, Sarana Chatushtai.

The madhyama-grama is the same, but the panchama (Pa) has to be diminished by one shruti. That is, the panchama of madhyama-grama is lower than that of shadja-grama by one shruti according to Bharata. Shruti is only mentioned as a perceptual measure in the music of Bharata's time.

Shruti is better understood with the following explanation. In both the gramas, Ri is three shrutis away from Sa – there are three perceptible intervals between Sa and Ri. The third of these is called trishruti rishabha (Ri). Likewise, the second interval is called dvishruti rishabha, and the first ekashruti rishabha.

Notes at nine and 13 shrutis from each other are mutually samvādi (consonant). The notes that are at the distance of two and 20 shrutis are mutually vivādi (dissonant). The remaining ones, at the distance between 2 and 20 shrutis, are called anuvādi (assonant).

The shruti table below shows the mathematical ratios considered to correspond to the system described by Bharata and Dattila, along with the comparable notes in common Western 12-TET tuning and comparable notes in 53-TET tuning, and the names of the 22 shrutis provided by Śārñgadeva.

Shrutis 12-TET Notes 53-TET Notes Perfect FIFTHs
Name Ratio Cents Frequency
(Hz)
Name Frequency
(Hz)
Note
No.
Frequency
(Hz)
FIFTH
No.
Frequency
(Hz)
Kṣobhinī 1 0 261.6256 C 261.6256 0 261.6256 0 261.6256
Tīvrā 256/243 90 275.6220 C 277.1826 4 275.6763 -5 275.622
Kumudvatī 16/15 112 279.0673 5 279.3053 7 279.3824
Mandā 10/9 182 290.6951 D 293.6648 8 290.4816 -10 290.3672
Chandovatī 9/8 203 294.3288 9 294.3056 2 294.3288
Dayāvatī 32/27 294 310.0747 D 311.1270 13 310.1114 -3 310.0747
Ranjanī 6/5 316 313.9507 14 314.1937 9 314.3052
Raktikā 5/4 386 327.0319 E 329.6275 17 326.7661 -8 326.6631
Raudrī 81/64 407 331.1198 18 331.0677 4 331.1199
Krodhā 4/3 498 348.8341 F 349.2282 22 348.8478 -1 348.8341
Vajrikā 27/20 519 353.1945 23 353.4401 11 353.5933
Prasāriṇī 45/32 590 367.9109 F 369.9944 26 367.5829 -6 367.496
Prīti 729/512 612 372.5098 27 372.4218 6 372.5098
Mārjanī 3/2 702 392.4383 G 391.9954 31 392.4229 1 392.4384
Kṣiti 128/81 792 413.4330 G 415.3047 35 413.4982 -4 413.433
Raktā 8/5 814 418.6009 36 418.9415 8 419.0736
Sandīpanī 5/3 884 436.0426 A 440.0000 39 435.7053 -9 435.5508
Ālāpinī 27/16 906 441.4931 40 441.441 3 441.4932
Madantī 16/9 996 465.1121 A 466.1638 44 465.1488 -2 465.1121
Rohiṇī 9/5 1017 470.9260 45 471.2721 10 471.4578
Ramyā 15/8 1088 490.5479 B 493.8833 48 490.1298 -7 489.9947
Ugrā 243/128 1110 496.6798 49 496.582 5 496.6798
Kṣobhinī 2 1200 523.2511 C 523.2511 53 523.2512 0 523.2511

The 53-TET approximation has an maximum error of 1.5 cents, while the perfect fifths approximation has an maximum error of 2 cents.

The table below shows the Harmonic scales into shruti:

Name Frequency
(Hz)
Normalized
(Freq/261.6256)
HARMONIC MULTIPLES = Normalized x n
(n = 2,3,4,5,6,8,9,10,12,15,16,18,19,20,24,25,27,30,32)
Kṣobhinī 261.6256 1.000000 2 3 4 5 6 8 9 10 12 15 16 18 19 20 24 25 27 30 32
Tīvrā 275.622 1.053498 20
Kumudvatī 279.0673 1.066667 16 32
Mandā 290.6951 1.111111 10 20 30
Chandovatī 294.3288 1.125000 9 18 27 36
Dayāvatī 310.0747 1.185185 32
Ranjanī 313.9507 1.200000 6 12 18 24 30 36
Raktikā 327.0319 1.250000 5 10 15 20 25 30 40
Raudrī 331.1198 1.265625 24
Krodhā 348.8341 1.333333 4 8 12 16 20 24 32 36 40
Vajrikā 353.1945 1.350000 27
Prasāriṇī 367.9109 1.406250 45
Prīti 372.5098 1.423828 27
Mārjanī 392.4383 1.500000 3 6 9 12 15 18 24 27 30 36 45 48
Kṣiti 413.433 1.580247 16 30
Raktā 418.6009 1.600000 8 24 32 40 48
Sandīpanī 436.0426 1.666666 5 10 15 20 25 30 40 45 50
Ālāpinī 441.4931 1.687500 32 54
Madantī 465.1121 1.777777 16 32 48
Rohiṇī 470.926 1.800000 9 18 27 36 45 54
Ramyā 490.5479 1.875000 15 30 45 60
Ugrā 496.6798 1.898437 36
Kṣobhinī 523.2511 2.000000 4 6 8 10 12 16 18 20 24 30 32 36 38 40 48 50 54 60 64

As it show, the harmonics in scales of shruti are multiples of prime numbers 2, 3, 5 and 19. There's not multiples of 7, 11, 13, 17, 23, etc., just of 19 so that's too weird. Really it's not 19, but 19.2, because 19.2/32 = 3/5, which means that when we use the harmonic 19.2, it becomes the harmonic 3, and all of the harmonics multiplies up by 5.

Medieval period: Mela system[edit]

By the time Venkatamakhin formulated the melakarta ("mela") system, the grama system was no longer in use. Unlike the grama system, the mela system uses the same starting swara. It forms the scales by varying the intervals of the subsequent swaras, and does not specify a fixed interval for a swara in terms of shrutis. For example, the intervals of kakali-nishada and shuddha-madhyama would vary depending on the dhaivata and the gandhara that precede them, respectively. The interval of kakali-nishada would be of three different shruti values depending on whether shuddha, panca-sruti or shat-shruti-dhaivata preceded it. Thus shruti as a measure of interval is not fully utilized in the mela system.

Modern period: Controversy[edit]

The mela system still prevails. The term shruti in current practice of Carnatic music, has several meanings.[3] It is used by musicians in several contexts. For instance, the Tamil term "Oru kattai sruti" would mean that the tonic is set to the pitch C or the first key. The Telugu term "Sruti chesuko (శ్రుతి చేసుకో)" is a way to correspond with the accompanying artists to tune their instruments.

The term has also undergone a gross misunderstanding. In certain ragas, due to inflexions or gamakas on few of those 12 notes, listeners perceive a sharpened or flattened version of an existing note.[4] Some scholars have attempted to fit such perceived new tones into the non-contextual Bharata's 22 shrutis, which lead to confusion and controversy over 22 shrutis. It was also wrongly attributed to Bharata, who proposed shruti in a completely different context.

There is scientific evidence that shows that these intermediate tones perceived in the contemporary rendition of a raga does not hint at the existence of 22 shrutis. The number 22 is of no practical significance in the current performance of Carnatic and Hindustani music traditions, partly because different musicians use slightly different "shrutis" when performing the same raga. The phenomenon of intermediate tones is pursued as an active area of research in Indian Musicology, which says the number of perceptible intermediate tones may be less or even much more than 22.[4] N. Ramanathan, a musicologist points it out and says that the idea of 22 shrutis is applicable only to the music system of Bharata's time.

The sufficiently new Indian monograph about shruti say there had been various opinions about the number (66, 53) of shrutis, but in recent times it seems that the number of shrutis is broadly agreed upon as 22. Recognizing the existing some controversy over the numbers and the exact ratios of the shruti intervals, it also say that all shrutis are not equal[5] and known as nyuna shruti (22 cents), pramana shruti (70 cents) and purana shruti (90 cents).[6] Еach shruti may be approximated in 53EDO system.[7]

Ancient treatises on Indian classical music and performing arts[edit]

References[edit]

  1. ^ Bakshi, Haresh. 101 Raga-s for the 21st Century and Beyond: A Music Lover's Guide to Hindustani Music. 
  2. ^ Ramanathan, N. Sruti in Ancient, Medieval and Modern Contexts, an article from musicresearch.in
  3. ^ Krishnaswamy A. Inflexions and Microtonality in South Indian Classical Music. Frontiers of Research on Speech and Music, 2004.
  4. ^ a b Krishnaswamy A. On the twelve basic intervals in South Indian classical music. AUDIO ENGINEERING SOCIETY. 2003
  5. ^ Datta, A. K.; Sengupta, R., Dey, N. and Nag, D (2006). Experimental Analysis of Shrutis from Performances in Hindustani Music. Kolkata, India: SRD ITC SRA. p. 19. ISBN 81-903818-0-6. 
  6. ^ Ibidem. p. 28. 
  7. ^ Khramov, Mykhaylo (December 2011). "On Amount of Notes in Octave". Ninaad, Journal of the ITC-SRA (Kolkata, India) 25: 31–37. ISSN 0973-3787.