Model reference · open weights

japanese-hubert-k2-rs35kh

Available as managed deployment Audio reazon-research Speech→text 1 variants 542 dl/mo

japanese-hubert-k2-rs35kh is an open-weight audio or speech model from reazon-research. AxForge deploys and operates it for you on dedicated EU-owned hardware — with the licence handled where one is required.

Available as managed deployment — configured and operated for you on dedicated EU hardware, quoted per deployment.

What it is

Released byreazon-research
TypeAudio & music
TaskSpeech→text
Parameters (lead)98M
Runs withtransformers
Based onreazon-research/japanese-hubert-base-k2
Released2025-09-29
Popularity542 downloads / month
LicenceOpen weights

About

What japanese-hubert-k2-rs35kh is

This model is a Hubert Base fine-tuned on the large-scale Japanese ASR corpus ReazonSpeech v2.0 using the k2 framework.

Read the full model card

Usage

You can use this model through transformers library:

import librosa
import numpy as np
from transformers import AutoProcessor, HubertForCTC

model = HubertForCTC.from_pretrained(
    "reazon-research/japanese-hubert-base-k2-rs35kh",
    torch_dtype=torch.bfloat16,
    attn_implementation="flash_attention_2",
).to("cuda")
processor = AutoProcessor.from_pretrained("reazon-research/japanese-hubert-base-k2-rs35kh")

audio, _ = librosa.load(audio_filepath, sr=16_000)
audio = np.pad(audio, pad_width=int(0.5 * 16_000))  # Recommend to pad audio before inference
input_values = processor(
    audio,
    return_tensors="pt",
    sampling_rate=16_000
).input_values.to("cuda").to(torch.bfloat16)

with torch.inference_mode():
    logits = model(input_values).logits.cpu()
predicted_ids = torch.argmax(logits, dim=-1)[0]
transcription = processor.decode(predicted_ids, skip_special_tokens=True)

Test Results

We report the Character Error Rate (CER) of our model and the other wav2vec2 families.

Model#Prameters⬇AVERAGE⬇JSUT-BASIC5000⬇Common Voice⬇TEDxJP-10K⬇
reazon-research/japanese-wav2vec2-large-rs35kh319M16.25%11.00%18.23%19.53%
reazon-research/japanese-wav2vec2-base-rs35kh96.7M20.40%13.22%23.76%24.23%
reazon-research/japanese-hubert-base-k2-rs35kh98.4M11.23%9.94%11.59%12.18%
reazon-research/japanese-hubert-base-k2-rs35kh-bpe98.4M11.07%9.76%11.36%12.10%

We also report the CER for long-form speech.

Model#Prameters⬇JSUT-BOOK⬇
reazon-research/japanese-wav2vec2-large-rs35kh319M30.98%
reazon-research/japanese-wav2vec2-base-rs35kh96.7M82.84%
reazon-research/japanese-hubert-base-k2-rs35kh98.4M27.05%
+ Silero VAD19.59%
reazon-research/japanese-hubert-base-k2-rs35kh-bpe98.4M84.55%
+ Silero VAD19.34%

Citation

@misc{japanese-hubert-base-k2-rs35kh,
  title={japanese-hubert-base-k2-rs35kh},
  author={Sasaki, Yuta},
  url = {https://huggingface.co/reazon-research/japanese-hubert-base-k2-rs35kh},
  year = {2025}
}

@article{yang2024k2ssl,
  title={k2SSL: A faster and better framework for self-supervised speech representation learning},
  author={Yang, Yifan and Zhuo, Jianheng and Jin, Zengrui and Ma, Ziyang and Yang, Xiaoyu and Yao, Zengwei and Guo, Liyong and Kang, Wei and Kuang, Fangjun and Lin, Long and others},
  journal={arXiv preprint arXiv:2411.17100},
  year={2024}
}

License

Apache Licence 2.0

From the published model card. Full card on the HuggingFace links in the sidebar.

Using it via the API

Call it like any OpenAI endpoint

Once AxForge deploys japanese-hubert-k2-rs35kh for you, it answers on the OpenAI-compatible API — the same base URL and keys as every other model. (japanese-hubert-k2-rs35kh below is illustrative; you get the exact model name on deployment.)

$ curl -sS https://api.axforge.ai/v1/audio/transcriptions \
  -H "Authorization: Bearer $AXFORGE_API_KEY" \
  -F model="japanese-hubert-k2-rs35kh" -F file=@audio.mp3

Create an account — your API key is available in the console. 3M free tokens every 30 days with every new account.

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