---
title: "Exploring Non-Autoregressive End-To-End Neural Modeling For"
description: "The authors replace the autoregressive recognizer with a non-autoregressive \"dictation model\" built on… 30 references, cited by 1 paper here."
authors: ["Hsin-Wei Wang", "Bi-Cheng Yan", "Hsuan-Sheng Chiu", "Yung-Chang Hsu", "Berlin Chen"]
year: 2021
venue: "arXiv:2111.00844"
source: "https://arxiv.org/abs/2111.00844"
doi: "10.48550/arxiv.2111.00844"
arxiv: "2111.00844"
licence: "arXiv — non-exclusive license to distribute"
licence_url: "http://arxiv.org/licenses/nonexclusive-distrib/1.0/"
summary_licence: "Elamur Cosmic License"
canonical: "https://research.elamur.ai/free/en/papers/wang-2021-exploring-non-autoregressive-end-end/"
---
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# Exploring Non-Autoregressive End-To-End Neural Modeling For English Mispronunciation Detection And Diagnosis

**Authors:** [Hsin-Wei Wang](https://md.research.elamur.ai/free/en/authors/hsin-wei-wang/), [Bi-Cheng Yan](https://md.research.elamur.ai/free/en/authors/bi-cheng-yan/), Hsuan-Sheng Chiu, [Yung-Chang Hsu](https://md.research.elamur.ai/free/en/authors/yung-chang-hsu/) and [Berlin Chen](https://md.research.elamur.ai/free/en/authors/berlin-chen/) · **Year:** 2021 · **Venue:** arXiv:2111.00844 · **Licence:** [arXiv — non-exclusive license to distribute](http://arxiv.org/licenses/nonexclusive-distrib/1.0/)

**Links:** [Publisher's page](https://arxiv.org/abs/2111.00844) · [PDF](https://arxiv.org/pdf/2111.00844) · [DOI 10.48550/arxiv.2111.00844](https://doi.org/10.48550/arxiv.2111.00844) · [arXiv 2111.00844](https://arxiv.org/abs/2111.00844) · [OpenAlex](https://openalex.org/W4291331905)

**Citations:** 1 citations (OpenAlex, 2026-10-14) · 1 in our library, of the 149,439 papers whose bibliographies we read

## Summary
The paper targets computer-assisted pronunciation training. The task is to find phone-level mispronunciations in L2 English speech and say what went wrong (MD&D). Common end-to-end systems such as CTC-ATT decode phones left to right with beam search. That makes them slow, and they also suffer when non-native training data is scarce.

The authors replace the autoregressive recognizer with a non-autoregressive "dictation model" built on Mask-CTC. A Conformer encoder with CTC produces an initial phone string. Phones with low confidence are then masked and refilled in parallel by a conditional masked language model that sees context on both sides.

On top of this they add a separate "pronunciation model". It takes the dictated phones and their confidence scores and checks them against the canonical phones of the prompt text, using a prompt-modulated gating mechanism. The system is trained on L2-ARCTIC plus TIMIT.

With wav2vec 2.0 features, the dictation model comes close to the phone error rate of CTC-ATT at a small fraction of its real-time factor. This shows that fast, deployable feedback for learners is feasible.

## Key points
- **Data.** L2-ARCTIC covers 24 non-native speakers with six mother tongues: Hindi, Korean, Mandarin, Spanish, Arabic and Vietnamese.
  - Split by speakers: 17 train, 1 dev and 6 test, with 900 test utterances.
  - TIMIT native speech was pooled into training.
- **Phone inventory.** Training uses 48 phones, each paired with an "anti-phone" that marks distorted, in-between realizations. At test time the inventory is collapsed to 39 phones to stay comparable with earlier work.
- **Dictation model.** It is trained with a joint CTC plus mask-predict objective, using Mask-CTC with a Conformer encoder and a Transformer-based CMLM.
- **Pronunciation model.** Each phone embedding is concatenated with its confidence score and passed through a Transformer encoder. A GRU turns the canonical prompt phones into one embedding, which gates every phone vector through sigmoid gating and ReLU. A final FFN with softmax makes the decision.
- **Speed and accuracy.** On L2-ARCTIC, accuracy is measured as PER (the share of phones recognized wrongly) and speed as RTF (the real-time factor):

  | Model | PER | RTF |
  |---|---|---|
  | CTC-ATT, beam 1 | 15.2% | 3.10 |
  | CTC-ATT, beam 10 | 14.9% | 13.85 |
  | Mask-CTC, FBANK features | 22.6% | 0.05 |
  | Mask-CTC, wav2vec 2.0 features | 15.9% | 0.05 |

  The choice of acoustic features clearly matters for accuracy, while speed stays the same.

## Interesting ideas
- **Draft, mask, refill.** Make a fast first draft of the whole sequence, mask only the low-confidence items, and refill them in parallel from confident context on both sides; this avoids slow sequential decoding while still fixing weak spots.
- **Separate recognizing from judging.** Instead of directly diffing the recognized output against the reference, a second model decides correctness from the output, its confidence and the reference, which makes it robust to a recognizer that overfits.
- **Anti-labels for in-between errors.** Each canonical class gets a companion label for "distorted version of X", so non-categorical errors are not forced into a wrong class.
- **Reference-conditioned gating.** A single summary vector of the expected reference gates every element of the observed sequence, so each item is judged relative to what should have been there.
- **Train fine, evaluate coarse.** Train on a fine-grained label set but collapse it to a standard coarser set for evaluation, keeping detail internally while staying comparable to prior work.

## For Mova

How these ideas could serve Mova, our small open language model — its files, stages and tests:

- **I1** (tree): gparse could emit a full parse, mask arcs or labels below a confidence threshold, and re-predict only those given the confident arcs, logging each revision as an explainable repair.
- **I2** (learn): a judge that sees a parse, per-arc confidence and the witness parsers' outputs could decide which arcs enter silver data, rather than relying on plain agreement counts.
- **I3** (tokens): the tagger and morphology could carry an "off-form of X" tag for misspellings, dialect or learner forms, keeping the intended lemma while flagging the deviation.
- **I4** (answer): when grading student answers in school-course tests, the frames of the expected answer could gate how each extracted student frame is scored, with the gate values kept as an explanation.
- **I5** (learn): train on Mova's richer internal relation labels but report on collapsed plain UD labels, so benchmark numbers stay comparable without losing internal distinctions.

*Our summary of the paper, in our own words — not its text. The work belongs to its authors; read it at the links above.*

## Institutions

- [National Taiwan Normal University](https://md.research.elamur.ai/free/en/universities/national-taiwan-normal-university/) — University, Taipei, Taiwan · 7 works · 119 citations
- [Chunghwa Telecom](https://md.research.elamur.ai/free/en/companies/chunghwa-telecom/) — Company, Taipei, Taiwan · 2 works · 2 citations

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🧭 Topics (1): [English](https://md.research.elamur.ai/free/en/topics/english/) · 2,379 works

## Cite

Cite as: Hsin-Wei Wang, Bi-Cheng Yan, Hsuan-Sheng Chiu, Yung-Chang Hsu and Berlin Chen. 2021. Exploring Non-Autoregressive End-To-End Neural Modeling For English Mispronunciation Detection And Diagnosis. arXiv:2111.00844.

The paper itself, not this page. BibTeX from the library's record of the work.

```bibtex
@misc{wang2021exploring,
  title = {{Exploring Non-Autoregressive End-To-End Neural Modeling For English Mispronunciation Detection And Diagnosis}},
  author = {Hsin-Wei Wang, Bi-Cheng Yan, Hsuan-Sheng Chiu, Yung-Chang Hsu and Berlin Chen},
  year = {2021},
  doi = {10.48550/arxiv.2111.00844},
  eprint = {2111.00844},
  archivePrefix = {arXiv},
  url = {https://doi.org/10.48550/arxiv.2111.00844}
}
```

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## References

30 references, 7 of them with a card of ours. ↗ leads to the work, «find» searches for one we have no id for yet.

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*Updated 2 November 2026*
