General Theory and Acoustics
This domain tests basic sound theory applied to Hindustani vocal music: nada, pitch, loudness, timbre, resonance, shruti and the difference between natural and equal-tempered tuning. Numerical questions on frequency ratios are common.
Core rules
- Nada is sound. Ahata nada is produced by a strike or effort; anahata nada is unstruck or internal. Musical nada has regular vibration.
- Pitch depends on frequency; loudness depends on amplitude; timbre depends on the harmonic spectrum. Do not confuse loudness with pitch.
- The octave is a 2:1 frequency ratio. In just intonation, Pa is 3:2 above Sa and Ma is 4:3.
- Bharata's tradition names 22 shrutis, but modern practical scales use twelve semitones. Shruti is a theoretical microtonal unit, not simply a synonym for semitone.
- Equal temperament divides the octave into twelve equal semitones; Hindustani vocal music often favours natural interval ratios and raga-specific intonation.
Worked example
If Sa is 240 Hz, find Pa and the upper Sa. Pa is 3:2 of Sa: 240 x 3/2 = 360 Hz. Upper Sa is 2:1: 240 x 2 = 480 Hz. Reasoning: ratios are measured from the tonic, not from the previous note. The upper Sa is exactly double the frequency of the lower Sa, which is why it is the same swara in the next saptak.
Traps
- Saying a louder note is higher in pitch; amplitude and frequency are different.
- Treating the 22 shrutis as 22 equal semitones.
- Calculating Pa as 240 + 3/2 instead of multiplying by 3/2.
- Assuming equal temperament and just intonation give identical interval sizes.