Who said what, in 40 languages: NVIDIA opens up Nemotron 3.5 Transcribe and its data recipe ๐️
Speech-to-text has quietly become one of the most useful AI tools I use. But a plain transcript often isn't enough. In a meeting you want to know who said what, in a class you want to jump to the moment something was explained, and in a doctor's office you want "HbA1c" spelled correctly. On 28 October, NVIDIA released Nemotron 3.5 Transcribe on Hugging Face and ModelScope, together with Granary v2, the open data pipeline behind it. I really like how much of the recipe they shared.
One model, several jobs
Transcribe is a single promptable checkpoint for transcription, speaker attribution, translation and audio question answering. According to NVIDIA's announcement, it transcribes 40 languages (Dutch is one of them), translates 31 of them to or from English, attributes speakers in 13, handles recordings up to an hour long and labels up to eight speakers.
You steer it with plain language, like "Transcribe this recording and label each speaker" or "What decisions were made in this meeting?" You can also give it a short list of possible terms, with the instruction to use them only when the audio supports them.
Under the hood, a speech encoder feeds a hybrid Mamba-Transformer mixture-of-experts language model. It has about 30B parameters in total, but only about 4B are active per token. Speaker cues from NVIDIA's Sortformer reach the language model together with the audio features, so it can tag each turn while it writes, instead of attaching speakers afterwards.
The numbers
NVIDIA reports 5.33% average word error rate on the English track of the Hugging Face Open ASR Leaderboard, first among open-weight models. On Artificial Analysis's independent speech-to-text index it ties for first among open models at 2.8%, with roughly a sixth of the active parameters of the model it ties. It also posts the lowest diarization error rate (18.26% across 21 languages) on David AI's multilingual leaderboard. In NVIDIA's own benchmarking, the upcoming NVFP4 version processed 100 hours of audio in under three minutes on a single RTX PRO 6000 Blackwell GPU.
Why I find this exciting
For me, the best part is Granary v2. Its public manifest covers 463,062 hours of speech across 48 languages and 16 source corpora, up from 25 languages in the first version. Every recording gets three transcript styles, from verbatim with "uh" to clean, written-form text, plus quality flags and provenance. That's the kind of openness that lets others actually learn how a strong speech model gets built.
The adaptation story is just as practical. In a medical case study, a better prompt cut word error rate from 30.8% to 23.8%, and fine-tuning brought it down to 11.8%. On held-out speakers, the error rate dropped from 22.44% to 12.17%, and the whole adaptation took about 14 GPU-hours on one GB300.
And as someone who cares about education: Agora used the word-level timestamps to put a recorded class next to its transcript, so students can see what was said and when.
Honest notes
Transcribe works on recorded audio, not live streams. The licence is NVIDIA's OpenMDW-1.1, so read it before you build on it. Quantized versions and local deployment through NeMo-Speech.cpp are announced as coming soon, and audio question answering is trained in English only. NVIDIA itself recommends spot-checking names and speaker changes against the recording.
Sources
- NVIDIA Nemotron 3.5 Transcribe and Granary v2 (Hugging Face blog)
- Nemotron 3.5 Transcribe model card (Hugging Face)
- Voice AI in vogue: Nvidia releases new open transcription model (TechCrunch)
An open model is great. An open model plus the data pipeline and the fine-tuning recipe is even better, because it invites everyone to make it fit their own language and their own field.
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