Model reference · open weights

japanese-hubert-k2-rs35kh

Audio reazon-research Speech→text 1 build Open weights 542 dl/mo

japanese-hubert-k2-rs35kh is an open-weight audio or speech model from reazon-research. japanese-hubert-base-k2-rs35kh (FP32) weighs 197 MB; the smallest configuration that runs it is RTX 3060 12 GB.

For self-hosting, compare this build's requirements below with the GPU you plan to rent.

  • japanese-hubert-k2-rs35kh is a 98M parameter automatic speech recognition model developed by reazon-research for the Japanese language.
  • It is a Hubert Base architecture fine-tuned on the ReazonSpeech v2.0 corpus using the k2 framework.
  • The model is released under the Apache 2.0 license.

Summary of the reazon-research/japanese-hubert-base-k2-rs35kh model card, 2026-10-01

What it is

Released byreazon-research
Released2025-09-29
Parameters98M
VRAM197 MB for the weights

What it runs on

Memory and cards for japanese-hubert-base-k2-rs35kh (FP32)

197 MBweights, file size
1.6 GBruntime overhead
CardOne streamMemory
RTX 3060 12 GBfits11.6 GB
RTX 4060 Ti 16 GBfits15.4 GB
RTX 3090 24 GBfits23.4 GB
RTX 4090 24 GBfits23.4 GB
RTX 5090 32 GBfits31.0 GB
L40S 48 GBfits44.0 GB
A100 80 GBfits78.2 GB
H100 80 GBfits78.1 GB
RTX PRO 6000 Blackwell 96 GBfits93.8 GB
DGX Spark (GB10) 128 GB unifiedfits107 GB
H200 141 GBfits138 GB
B200 180 GBfits176 GB

From the model card

What reazon-research says about japanese-hubert-k2-rs35kh

Read the model card

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

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

Quoted from the model card on Hugging Face. The full card is behind the Hugging Face link above.

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