Śruti commonly refers to musical pitch.
I
While there are an infinite number of sounds falling within a scale (or raga) in Carnatic music, the number that can be distinguished by auditory perception is 22-twenty-two (although over the years, several of them have converged). In this sense, while sruti is determined by auditory perception, it is also an expression in the listener's mind.
Svara
Svara refers to a type of musical sound that is a single note, which defines a relative (higher or lower) position of a note, rather than a defined frequency.
Svaras also refer to the solfege of Carnatic music, which consist of seven notes, "sa-ri-ga-ma-pa-da-ni"
These names are abbreviations of the longer names shadja, rishabha, gandhara, madhyama, panchama, dhaivata and nishada.
Unlike other music systems, every member of the swara has three variants.
( The exceptions are the notes, shadja and panchama which have only one form; and madhyama (the subdominant), which has two forms. )
Ṣaḍjam (षड्जम्)
Śuddha R̥ṣabham (शुद्ध ऋषभम्)
Catuśruti R̥ṣabham (चतुश्रुति ऋषभम्)
Ṣaṭśruti R̥ṣabham (षट्श्रुति ऋषभम्)
Śuddha Gāndhāram (शुद्ध गान्धारम्)
Sādhāraṇa Gāndhāram
Antara Gāndhāram (अन्तर)
Śhuddha Madhyamam
Prati Madhyamam Ma
Pañcamam (पञ्चमम्) Pa
Śuddha Dhaivatam Dha
Catuśruti Dhaivatam
Ṣaṭśruti Dhaivatam
Śuddha Niṣādam (शुद्ध निषादम्) Ni
Kaiśikī Niṣādam
Kākalī Niṣādam