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STT En Conformer-CTC Small

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STT En Conformer-CTC Small is an open-weights speech-to-text model from NVIDIA, released June 2023. Its published size is 0.013B parameters. Licence: cc-by-4.0.

Catalogue identity notes

Exact checkpoint nvidia/stt_en_conformer_ctc_small (NeMo). Params: card (~13M). released: HF repo creation month.

38.9±3.2#139 of 162 speech-to-text modelsfrom 4 benchmark results across 2 sources

Score within the Open ASR English short-form WER (March 2026) comparison set only.

$ how it compares

The speech-to-text models ranked either side of STT En Conformer-CTC Small, out of 176 with a score, then more from NVIDIA.

#modelscorewhereRAMreleased
151ESPnet Multi-blank Transducer 8421 ESPnet40±4local~8GB2023-02
152ESPnet Conformer RNN-T (no LM) ESPnet40±4local~8GB2022-04
153STT En Conformer-CTC Small NVIDIA39±3local~0.6GB2023-06
154Whisper small OpenAI39±2local~1.1GB2022-09
155Moonshine Base Useful Sensors (Moonshine AI)38±3local~0.8GB2024-10
more from NVIDIA
28Canary-Qwen-2.5B NVIDIA61±2local~6.6GB2025-07
35Parakeet TDT 0.6B v2 NVIDIA60±1local~1.9GB2025-05
37Parakeet Unified EN 0.6B NVIDIA60±4local~0.7GB2026-04

see all speech-to-text models · find the ones that fit your machine

$ what it's good at

long-form transcription▁▁▄▁·▁▂█▄▁▁▁ #23 of 27 * · 35% of its score · 1 test

Beats STT En Conformer-Transducer Large, STT En FastConformer-Transducer Large, STT En FastConformer-CTC Large here, though they rank higher overall.

testresultvs the others in its rundifficultycountswhy
Open ASR English long-form WER15.3% ✎▁▁▅▁·▃▅█▆▁▂▂ beats 4/30avg 12%▇▇▇▇▇▇▇▇▇▇▇▇▇▇ 35%typical
other tests3 not in a task · 61% of its score
testresultvs the others in its rundifficultycountswhy
Open ASR English short-form WER (March 2026)11.2% ✎▁▁▁▃··▁▃▂██▆ beats 16/86avg 8.2%▇▇▇▇▇▇▇▇▇▇▇▇▇▇ 35%blunt
LibriSpeech test-other WER lab8.1% ✎▁▁▃▂▅▃▅▄█▂▂▁ beats 3/54avg 3.5%▇▇▇▇▇▇▇▇ 21%typical
LibriSpeech test-clean WER lab3.7% ✎▁·▁·▁▁▁▃▃▇█▆ beats 10/100avg 1.8%▇▇ 6.0%blunt

$ where to run it

Other ways to run it

  1. Run it as published · needs ~0.56 GB, NVIDIA only · from huggingface.co/nvidia (official)
    uvx --with 'nemo_toolkit[asr]' python -c "import nemo.collections.asr as a; print(a.models.ASRModel.from_pretrained('nvidia/stt_en_conformer_ctc_small').transcribe(['audio.wav']))"

Official weights and documentation: huggingface.co/nvidia ↗

$ how the score was worked out · Open ASR Leaderboard 69%, NVIDIA NeMo docs: ASR scores… 27%

Each result implies a score on its own, after adjusting for how hard its test is and who ran it. The score is their weighted average, with a small pull toward the middle for thinly tested models. Each test's weight is its counts column above; here it's added up by who ran the tests. How it works

sourceresultsshare of the scorelicence
Open ASR Leaderboard2▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇ 69%Apache-2.0
NVIDIA NeMo docs: ASR scores tables (English Conformer / FastConformer) · lab-reported2▇▇▇▇▇▇▇▇ 27%Apache-2.0
prior · pull toward the middle▇ 4%
weighted average= 38.9

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data updated · sources and licences · json