Why another error rate
Plain WER treats every mismatch as the same mistake. For Indic languages and
domain-heavy transcription that hides the story: an agglutinated word split in
two, a date written with different separators, and a misrecognized legal term
are three very different failures. SCRIBE decomposes tokens into base classes
and an optional domain class, aligns them with a category-aware algorithm,
and reports one error rate per class over a shared denominator.
| Category | Label | What lands here |
| LEXICAL | ER_LEX | General words, Indic and English |
| NUMERAL | ER_NUM | Numbers, dates, times — 302, 22.05.2023, 10:30 |
| PUNCT | ER_PUNCT | Punctuation marks |
| LEGAL / MEDICAL / TECH / custom | ER_DOMAIN | Domain terminology, shielded from incorrect splitting |
WER_SCRIBE is the composite: all category errors over the
combined reference-token denominator. CER_SCRIBE is a
character error rate computed on normalized token streams — format variants
cost nothing, and it needs no sandhi machinery to be robust to
agglutination.
Sandhi awareness
Agglutination makes word boundaries unstable in Indic text: the same speech
can be written as one word or two. SCRIBE detects such two-word merges and
splits at alignment time and scores them as matches instead of errors. Each
row below is real evaluation data — and each would count as 100% WER on its
phrase without detection.
| Language | Reference | Hypothesis | Junction | |
| Malayalam | കഥാപാത്രമായിട്ടാണ് | കഥാപാത്രം ആയിട്ടാണ് | compound split | Try it ↗ |
| Malayalam | എനിക്ക് അറിയാം | എനിക്കറിയാം | vowel elision | Try it ↗ |
| Kannada | ಪ್ರಧಾನ ಮಂತ್ರಿಗಳ | ಪ್ರಧಾನಮಂತ್ರಿಗಳ | compound merge | Try it ↗ |
| Kannada | ಮಿತ್ರರಾಷ್ಟ್ರಗಳು | ಮಿತ್ರ ರಾಷ್ಟ್ರಗಳು | compound split | Try it ↗ |
| Hindi | भाई साहब | भाईसाहब | compound spacing | Try it ↗ |
| Hindi | उस में | उसमें | postposition merge | Try it ↗ |
On an internal benchmark of 48 Malayalam legal dictations, sandhi detection
recovers 3.0 percentage points of WER_SCRIBE across 377
events that would otherwise masquerade as recognition errors. Detection is an
orthographic heuristic, not a linguistic analysis — deliberately lenient, with
documented limitations: see
scope
and limitations before relying on sandhi counts.