Bro-ASR-1.7B

Bro-ASR-1.7B is a merged, parameter-efficiently fine-tuned derivative of Qwen/Qwen3-ASR-1.7B-hf for Japanese noisy-recording/device-domain speech recognition. The repository contains full merged model weights; it does not require a separate LoRA adapter at inference time.

Intended use

• Offline Japanese ASR for noisy conversational recordings.
• Research and evaluation of device/noise-domain ASR adaptation.

It is not a safety-critical transcription system. Validate performance on your own audio domain before deployment.

Training

The model was produced by merging a LoRA adapter trained with the frozen lowrank_loraplus8_coverage recipe:

• Base model: Qwen/Qwen3-ASR-1.7B-hf
• Training pool: 3,000 Delivery_JP Japanese audio/text segments
• LoRA: rank 8, alpha 16, dropout 0.1, applied to attention and MLP projections
• LoRA+: base learning rate 8e-6, B-matrix ratio 8x
• Sampling: shuffle without replacement; 500 micro-steps, gradient accumulation 2

The Delivery_JP audio and transcripts are not included in this repository.

Dataset and evaluation

Evaluation uses the 20,619-segment Delivery_JP Japanese manifest. The shared 3,000-segment training/development pool is excluded before scoring, leaving a strictly unseen evaluation set of 17,619 segments. Both models were run on the same ordered sample_id list with identical normalized ground truth; each side produced exactly 17,619 predictions with no duplicate IDs.

Decoding uses a Japanese language hint, beam size 5, and max_new_tokens=256. CER is character-level Levenshtein distance after the same whitespace normalization for both models. Macro-CER is the unweighted mean of per-segment CER.

Model	Evaluated segments	Micro-CER	Macro-CER	Character errors	Exact-match rate
Base Qwen3-ASR-1.7B	17,619	0.34295	0.41445	102,563	14.995%
Bro-ASR-1.7B	17,619	0.33763	0.39566	100,970	18.208%

Compared with the base model, Bro-ASR-1.7B reduces Micro-CER by 0.533 percentage points and character errors by 1,593. On paired per-segment comparison, Bro-ASR-1.7B is better / unchanged / worse on 5,681 / 7,775 / 4,163 segments, respectively.

Fixed-set audit score comparisons

The following four models were evaluated on the identical frozen 1,000 sample_id values with identical normalized ground truth and exact fractional audio time boundaries. This fixed-set audit is separate from the 17,619-segment strict-unseen evaluation above.

Fixed audit subset	Model	Segments	Micro-CER	Macro-CER	Character errors	Exact-match rate	Decoding
Delivery_JP frozen 1,000	Bro-ASR-1.7B	1,000	0.47119	0.49852	7,581	14.4%	Japanese, beam 5
Delivery_JP frozen 1,000	Qwen3-ASR-1.7B baseline	1,000	0.48574	0.54712	7,815	10.3%	Japanese, beam 5
Delivery_JP frozen 1,000	Cohere Transcribe 03-2026	1,000	0.56871	0.63912	9,150	7.1%	Official model.transcribe, ja, punctuation, greedy
Delivery_JP frozen 1,000	Whisper large-v3-turbo (untrained)	1,000	1.53969	3.86799	24,772	0.7%	Historical frozen TTA: speed factors 1.0/0.95/1.05, Japanese, beam 5

On this 1,000-segment audit, Bro-ASR-1.7B reduces Micro-CER by 1.454 percentage points and character errors by 234 relative to the paired Qwen baseline. The Cohere run used the official native transcription entry point with EOS handling; Qwen and Bro-ASR both used Japanese beam size 5.

The Whisper row is the untrained base model, not the historical Plan B fine-tuned checkpoint. It was reproduced with the frozen best_solution_snapshot.py TTA decoder and an asserted zero LoRA B-matrix. Its result is substantially weaker on this audit; the decode policy is reported separately because it uses three TTA speed factors while the Qwen runs use beam-5 decoding.

Quick start

Qwen3-ASR is not included in older stable Transformers releases. Install the current Transformers source first, as recommended by the upstream Qwen3-ASR model card:

pip install "git+https://github.com/huggingface/transformers"
pip install torch soundfile

import torch
from transformers import AutoModelForMultimodalLM, AutoProcessor

model_id = "Junlaii/Bro-ASR-1.7B"
processor = AutoProcessor.from_pretrained(model_id)
model = AutoModelForMultimodalLM.from_pretrained(
    model_id, torch_dtype=torch.bfloat16, device_map="auto"
).eval()

inputs = processor.apply_transcription_request(
    audio="sample.wav", language="ja"
).to(model.device, model.dtype)
with torch.inference_mode():
    output = model.generate(**inputs, num_beams=5, max_new_tokens=256)
text = processor.decode(
    output[:, inputs["input_ids"].shape[1]:], return_format="transcription_only"
)[0]
print(text)

Limitations

• The current adaptation is specifically motivated by Japanese noisy-recording conditions; it may regress on other languages or acoustic domains.
• The full strict-unseen Delivery_JP evaluation has completed on 17,619 segments under the protocol described above.
• Decoding settings affect results. The final comparison uses Japanese, beam size 5, and max_new_tokens=256.

License and attribution

Bro-ASR-1.7B follows the Apache-2.0 license indicated by its base checkpoint. Please cite and follow the upstream Qwen3-ASR model terms when using this model.