Sapta is a Sanskrit word which means seven. So a saptak in Hindustani music means comprising of seven notes. It is a Sanskrit word for an Octave. In saptak or Octave there are 7 natural or pure notes along with their 5 low and high variants. The sevan pure notes and their 5 variants make 12 in all. If we see roughly, they are only the seven notes with their variants hence the word Saptak.
‘Do’ ‘Re’ ‘Mi’ ‘Fa’ ‘So’ ‘La’ ‘Ti’ – English
‘Sa’ ‘Re’ ‘Ga’ ‘Ma’ ‘Pa’ ‘Dha’ ‘Ni’ – Hindi
Octaves In Indian Classical Music
There are mainly three octaves used in Hindustani classical music.
Madhya Saptak (Middle or the 4th Octave)
This octave starts with C4, the ‘Scientific Pitch‘, termed as the ‘Shadaj‘ or ‘Sa‘ which has frequency of 256Hz.
The notes on the scale after that are placed accordingly.
Middle Ocatve Pure notes are denoted as
Sa, Re, Ga, Ma, Pa, Dha, Ni
Mandra Saptak (lower Octave or the 3rd octave)
In the lower Octave the frequency of notes is 2x lower (1 octave lower) than in the Madhya Saptak (middle octave). While writing these notes in notation, they are denoted bearing a dot below them:
Taar Saptak( Upper or the 5th octave)
Taar Saptak or Upper Octave:
In the upper Octave the frequency of the notes is 2x higher (1 octave higher) than in the Madhya Saptak (middle octave).
In notation these notes are denoted bearing a dot above them:
In addition to these Octaves, Indian classical vocalists and instrumentalist use Ati Mandra saptak or the 2nd octave while singing or playing instruments.