Neraval

Niraval also known as Neraval or Sahitya Vinyasa is considered to be one of the important features in the extempore improvisation aspect (Manodharma Sangita) of Carnatic music. The actual word is "Neravulu" (నెరవులు), which literally means expansions or elaborations.

Niraval is essentially the extempore construction, elaboration and improvisation of melody for a particular line in the kriti, within the framework of a talam which brings out the Raga bhava effectively. It is usually just one line from the charanam part of the kriti and has to sit within the framework of a tala and highlight every rasa and bhava singularly.

For example : 4-beat niravals for Shyama Sastri's "sarojadala netri himagiri putri" set to Adi talam (double) in the Raga Shankarabharanam can be constructed for the line "sama gana vinodhini guna" (like this : gpmgrs | s,ndpmgrs) in the charanam of the song.

Repetition of the line in different ways within the entire range of the Raga phrases brings out the musician's imagination.

Palghat K. V. Narayanaswamy was known and is remembered today as a master of niraval singing.

Ideally, the line taken up for neraval must convey a complete message. A textbook example of a line which does not satisfy this criterion is the charanam of Swathi Thirunal's composition, Deva Deva Kalayami in the raga Mayamalavagowla. Musicians commonly use the line Jadharupa Nibhachela Janmaarchitha Mamakhila as a base for neraval. However, the line itself is not a complete sentence, and therefore ill-suited for neraval. Instead, a singer should either take up the first eight avarthanas(Tala cycles) of the charanam which give a complete meaning, or choose a different, more suitable line in the composition.

Often times, the line chosen for neraval may contain several sentence fragments that have complete meaning by themselves, allowing the singer to strategically drop certain words or phrases and fill in the space with small amounts of alapana, while still making grammatical sense. An example of a krithi with such a line is Thyagaraja's Enati Nomu Phalamu, the charana of which begins Sundaresha Sugunabrinda Dasharathanandana Aravindanayana Paavana. Each word in this sentence is, by itself, an epithet of Lord Rama, and therefore conveys a complete meaning; the singer can drop certain words as they like without damaging the linguistic integrity of the line.

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Wikipedia