FastConformer-Quran

State-of-the-art automatic speech recognition for Quranic recitation, with a multi-signal mispronunciation detector built on top.

🚀 0.029% WER on EveryAyah test (Hafs riwayah). 13× better than the public Tarteel Whisper on the same audio. 🎯 82% sensitivity at 7% FPR on a 39K-token held-out mispronunciation benchmark. 📱 iOS-ready via the companion CoreML repo: Muno459/fastconformer-quran-coreml.

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Headline numbers

Word and character error rates on EveryAyah test (500 clips, CTC decoder)

Model	WER loose	WER strict	CER strict	RTF
FastConformer-Quran (this model)	0.029%	0.175%	0.027%	0.0012
Tarteel Whisper (tarteel-ai/whisper-base-ar-quran)	0.380%	0.409%	0.080%	0.0199
Tarteel Whisper published claim	5.7544%	n/a	n/a	n/a

13× better WER and 16× faster on the same hardware.

Zero-shot reciter generalization (1,760 clips, 36 reciters)

Of the 36 reciters in the EveryAyah test split, 30 have zero training samples in our manifest:

Group	Clips	This model	Tarteel Whisper	Ratio
Seen reciters (5)	300	0.186%	0.876%	4.7×
Unseen reciters (30)	1,460	0.230%	0.635%	2.8×
Aggregate	1,760	0.222%	0.676%	3.0×

Perfect (0.000%) WER on 16 zero-shot reciters including alafasy, husary, minshawi, mahmoud_ali_al_banna, mustafa_ismail, ahmed_ibn_ali_al_ajamy, and akram_alalaqimy. The model is not memorizing voices.

Phone-mic / user audio (tlog held-out, 800 clips, CTC)

Metric	Value
WER loose	21.24%
CER loose	5.79%
WER strict	40.91%
CER strict	8.47%

The tlog dataset has substantial label noise (filename to ayah mismatches, user-added basmala, partial recitations). A portion of the apparent WER is the model correctly transcribing what was said with the metadata being wrong.

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Demo audio

Alafasy reciting Q 1:4:

Predicted: مَالِكِ يَوْمِ الدِّينِ ✓

Abdullah Basfar reciting Q 112:1:

Predicted: قُلْ هُوَ اللَّهُ أَحَدٌ ✓

Alafasy reciting Q 78:2:

Predicted: قُلْ هُوَ نَبَأٌ عَظِيمٌ ✓

Try the live demo: Space.

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Mispronunciation detection

We also ship a multi-signal pronunciation scorer combining three orthogonal signals on the same CTC architecture:

Signal	What it measures	Style-invariant
Pronunciation head v7	Learned P(token correctly pronounced) on 1.33 M-parameter MLP over encoder features	✓
Reference-anchor distance	Cosine distance to master qari centroid bank (multi-ayah aware)	partial
CTC GOP	log P(expected token) minus max log P(non-blank token), averaged over CTC interval	✓

A token is flagged by the consensus rule when at least 2 of 3 signals agree (default thresholds: head < 0.5, anchor > 0.20, GOP < -3.0).

Held-out evaluation

On 39,173 tokens from 996 tlog clips that were never seen by the pronunciation head during training, with per-token consensus labels from our ASR and ElevenLabs Scribe v2:

Detector	TPR @ 1% FPR	TPR @ 5% FPR	AUC
GOP (style-invariant)	72.4%	77.6%	0.969
Pronunciation head	73.7%	84.2%	0.953
Anchor distance (where bank covers)	0.7%	10.5%	0.732
Consensus (2 of 3)	n/a	n/a	82.2% TPR / 7.2% FPR

The combined detector catches ~82% of real mispronunciations at a 7% false-positive rate. This is the deployable operating point.

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What this model is and isn't

Is:

• The best published ASR for Quranic recitation in Hafs riwayah.
• A frame-level CTC model with 512-dim encoder features exposed for downstream scoring.
• Production-ready ONNX (fp32 437 MB, fp16 219 MB), running at RTF ~0.001 on an RTX 4090.
• Diacritic-aware: outputs fully harakat-marked Arabic text.

Isn't:

• A general Arabic ASR. Trained only on Quranic audio with a 1,024-token BPE tokenizer. Performance on dialectal, news, or conversational Arabic will be poor by design.
• A native streaming model. The offline model can be run on overlapping chunks for a responsive UX (~5-8 second latency), which is appropriate for ayah-by-ayah recitation. See the CoreML repo for the chunked-streaming pattern with Swift code. True token-by-token low-latency streaming would require a separately-trained cache-aware variant (multi-day GPU job, deferred).
• Trained for other qira'at. Hafs riwayah only.

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How it was built

Stage 1: base training on EveryAyah. Fine-tuned NVIDIA's stt_en_fastconformer_hybrid_large_pc from English-pretrained weights to Arabic + Quran on 22 K EveryAyah clips. Reached 0.0757% WER on the held-out test split.

Stage 2: pronunciation scoring stack. Built a per-token head on top of frozen encoder features (512-dim pooled + 64-dim token embedding + 16-dim Quran-phonology features into an MLP). Initial training on weak labels (CTC-vs-expected disagreement + GOP scores) plus master qari anchors (Husary, Abdul Basit, Alafasy clean recitations).

Stage 3: phone-audio fine-tune. Three rounds of low-LR continuation on EveryAyah and tlog: 22,585 clean clips, 6,869 high-quality tlog clips (full weight), 20,589 borderline tlog clips (half weight). LR schedule 1e-5, 5e-6, 2.5e-6 over six epochs total. Trend was monotonic improvement on a held-out tlog slice through round three, then saturated.

Stage 4: dual-ASR consensus labels. Ran ElevenLabs Scribe v2 over the 6,168 highest-quality tlog clips. Aligned Scribe transcripts vs. expected ayah text at the character level (diacritic-insensitive Levenshtein), then aligned vs. our ASR output. Asymmetric-trust consensus rule:

A token is labeled CORRECT if EITHER ASR or Scribe says correct. It is labeled WRONG only when BOTH agree wrong.

Result: 144,664 per-token labels at ~98.0% positive rate, with 6,789 ASR-vs-Scribe disagreements flagged as high-information tokens. Cost: ~$11 in ElevenLabs Creator-plan credits.

Stage 5: final pronunciation head. Retrained on encoder features extracted with the final ASR (consistent features for both consensus labels and master qari anchors).

Stage 6: tajweed rule engine. Pure-Python rule engine that takes the expected diacritized text, audio, and per-token alignment, producing per-letter tajweed feedback across 27 dispatched rules (noon sakinah, meem sakinah, madd typology, qalqalah sughra/kubra, ra tafkheem/tarqeeq, Allah lafdh, lam shamsiyyah, hamzat wasl, idgham types, leen letters, more).

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Architecture

• Backbone: NVIDIA FastConformer Large encoder + CTC head (114.6 M params)
• Tokenizer: SentencePiece BPE, 1,024 vocab + 1 blank = 1,025 output classes
• Audio: 16 kHz, log-mel features (80 channels)
• Decoder: CTC greedy_batched (frame-independent, noise-robust, deterministic)
• Output: token log-probabilities and 512-dim encoder features per output frame

CTC is the right decoder for this task: frame-level alignment for the pronunciation pipeline, no auto-correction that would mask user mispronunciations, faster inference, and the loose-WER ceiling on EveryAyah is already 0.029% so there's no quality reason to add decoder complexity.

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Quick start (CTC, ONNX)

import numpy as np, soundfile as sf, onnxruntime as ort, sentencepiece as spm

session = ort.InferenceSession("onnx/model_with_encoder.onnx",
                                providers=["CUDAExecutionProvider", "CPUExecutionProvider"])
sp = spm.SentencePieceProcessor(model_file="tokenizer.model")

wav, sr = sf.read("clip.wav")           # 16 kHz mono float32
features = log_mel(wav)                  # see tajweed/aligner.py for the pipeline
features = features[None, ...]           # (B=1, 80, T_in)
length = np.array([features.shape[2]], dtype=np.int64)

logprobs, encoder_features = session.run(
    ["logprobs", "encoder_output"],
    {"audio_signal": features, "length": length},
)
# encoder_features: (1, 512, T_out). Feed to the pronunciation head.
# logprobs:         (1, T_out, 1025). Argmax + CTC collapse to get tokens.

The full multi-signal scorer (CTC + head + anchor + GOP + tajweed) is in tajweed/full_scorer.py.

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Files

Path	Description
nemo/fastconformer-quran-phase4c.nemo	NeMo checkpoint (438 MB)
onnx/model.onnx	CTC-only ONNX, fp32 (437 MB)
onnx/model.fp16.onnx	CTC-only ONNX, fp16 (219 MB)
onnx/model_with_encoder.onnx	CTC + encoder features, fp32 (437 MB)
head/pronunciation_head.pt	Pronunciation head v7 (5.4 MB)
tajweed/	Python module: text analyzer, 27 rules, full scorer
tokenizer.model	SentencePiece tokenizer
model_config.yaml	NeMo model config
demo/	Three sample clips with known transcriptions

For iOS / CoreML deployment, see Muno459/fastconformer-quran-coreml.

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Datasets

• Tarteel EveryAyah (tarteel-ai/everyayah): CC-BY 4.0. ~30 K studio recitation clips.
• Tarteel tlog (tarteel-ai/tlog): gated. Real user phone recordings.

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License

Apache 2.0, matching the upstream FastConformer-Hybrid license.

Citation

@misc{fastconformer-quran-2026,
  title  = {FastConformer-Quran: Quranic ASR and unsupervised mispronunciation scoring},
  author = {Anon},
  year   = {2026},
  url    = {https://huggingface.co/Muno459/fastconformer-quran},
}