Does Sanskrit phonetics describe something a microphone can measure?
Pāṇini classifies the stop consonants क च ट त प by sthāna — the place in the mouth where the closure is made: velar, palatal, retroflex, dental, labial. That is a claim about articulation, made two and a half millennia before anyone could record a sound.
If the classification tracks something physical, the five places should leave distinguishable traces in the acoustic signal — in the burst released at the moment of opening, in the formant transitions into the following vowel, perhaps in pitch. This project records those five stops across vowels, measures those cues, and asks whether the five places separate.
Each speaker reads a fixed list: the pure vowels, then each of the five stops with each vowel. Every utterance is measured the same way regardless of where it came from — synthesised speech, a recording added by hand, or a volunteer upload. Provenance is recorded as metadata, never as a separate pipeline.
Measurements go into a CSV, and a classifier is asked the direct question: given these features, can you recover which consonant was spoken? Three feature sets are compared — burst and formant cues without pitch, pitch alone, and both together — with TTS and human voices scored separately.
204 utterances are indexed, 204 of them carried into the measurements, across 7 human recordings and one synthetic voice.
Vowels separate cleanly on formants. The five consonant places do not separate well on any feature set tried so far, and pitch adds essentially nothing to place over burst and formant cues alone.
These are presented as observations. The interpretation — whether this reflects a limit of the features, of the corpus size, of synthetic speech, or something about the classification itself — is deliberately left open.
The site holds two bodies of analysis, and they answer different questions rather than one superseding the other:
| The sthāna study | Voice & language survey | |
|---|---|---|
| varies | real speakers | 4 TTS voices, 3 languages |
| covers | 5 stops | the whole varṇamālā |
| vowels | अ इ उ ए ओ | अ इ उ |
| human audio | yes | none, by construction |
The sparśa grid in the sidebar navigates the survey. That is why picking ए or ओ there greys out the consonants — those per-varṇa pages were only ever built for अ, इ and उ.
Utterances reach one corpus three ways, and everything downstream treats them identically.