Śruti (music)

Shruti or śruti (ʃrut̪i), is a Sanskrit word, found in the Vedic texts of Hinduism where it means musical intonation and "what is heard" in general. It is also an important concept in Indian music, where it means the smallest interval of pitch that the human ear can detect and a singer or musical instrument can produce. The musical sruti concept is found in ancient and medieval Sanskrit texts such as the Natya Shastra, Dattilam, Brihaddesi, and Sangitaratnakara.

The swara differs from sruti concept in Indian music. A sruti is the smallest gradation of pitch representing the quality of frequency (timbre), while a swara is the selected pitches from which the musician constructs the scales, melodies and ragas. The Natya Shastra identifies and discusses twenty two sruti and seven swara per octave. Of the twenty two sruti, veena scholars identified the 4th sruti to be sa solfege, 7th to be ri, 9th as ga, 13th as ma, 17th as pa, 20th to be dha and 22nd as ni suddha svara. Theoretically, an infinite number of sruti are possible, and later music scholars of India increased the number of sruti in their studies.

It has been used in several contexts throughout the history of Indian music. Recent research has more precisely defined the term Shruti, its difference from Nada and Swara, and pinpointed positions on a string to play 22 shrutis.

The meaning of shruti varies in different systems.

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 gramas—shadja-grama and madhyama-grama. The notes (svaras) are separated by intervals, as measured in 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. Abhinavagupta describes an experiment to obtain the correct physical configuration of shruti in shadja grama, Sarana Chatushtai.

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