The Relevance of Text and Speech Features in Automatic Non-native English Accent Identification
Paper · 2018 · Sowmya Vajjala and Ziwei Zhou
Summary
The paper investigates whether a non-native English speaker's first-language accent can be recognised without phoneme or word recognition. It also asks whether audio cues hold up better than transcript-based text cues when the speaking topic changes. The authors use the spoken part of the public ICNALE corpus, which has 11 classes: ten Asian L1 backgrounds plus native English speakers. They compare two kinds of input:
- the generic acoustic descriptor set from the INTERSPEECH ComParE baseline, extracted with OpenSmile;
- word and character n-grams taken from the manual transcriptions.
Accuracy reaches roughly 90% in both settings, using SMO for audio and Multinomial Logistic Regression for text, once feature selection or SMOTE oversampling is applied. The key difference shows up when training on one prompt and testing on the other: the n-gram models drop sharply, while the acoustic models keep most of their accuracy. This matters because generic signal features need no language-specific recogniser and transfer across topics. That makes them a practical basis for accent-aware speech technology and for research on L1 influence.
Key points
- Data: ICNALE speech contains 4400 clips of about one minute each, recorded in response to two prompts, with plain-text transcriptions. The classes are unbalanced, ranging from 200 to 600 files per class.
- Audio features: 6373 OpenSmile ComParE descriptors gave 77.9% accuracy with all features. Adding SMOTE raised this to 90.8%. Theory-motivated subsets did much worse: formants 45.2%, voicing 42.0%, MFCCs 69.4%.
- Feature selection on audio:
- Information gain and Chi-square peak near 90% at about 3000 features.
- ReliefF reaches a similar level with about 2000 features.
- Adding more features pushes accuracy back toward 80%.
- Text features (MLR):
- word n-grams up to 3: 83.8%
- character n-grams up to 10 spanning word boundaries: 88.3%
- character n-grams within word boundaries only: 84.7%
- word and cross-boundary character n-grams combined: 88.9%
- Cross-prompt results:
- Character n-grams fall from about 88% under within-prompt CV to about 58%.
- Word n-grams fall to 41.8–52.6%.
- The best audio configuration (3500 information-gain features) holds at 87.3% and 85.8% across the two prompt directions.
Interesting ideas
- I1. Swapping the topic between training and testing exposes models that learned content instead of the target signal, since text n-grams collapsed while acoustic features did not.
- I2. Feature subsets that looked linguistically motivated (formants, voicing) did far worse than the full set, so intuitions about which features matter should be checked empirically.
- I3. Ranking features with simple filters showed accuracy rising to a peak and then declining as more features were added, so a mid-sized ranked subset beat both extremes.
- I4. Synthetic oversampling of rare classes improved within-prompt scores but did nothing for cross-prompt transfer, a reminder that balancing tricks can inflate in-domain numbers only.
- I5. The authors suggest that automatic transcription errors might themselves carry accent information that clean manual transcripts erase, treating system errors as signal rather than pure noise.
For Mova
How these ideas could serve Mova, our small open language model — its files, stages and tests:
- I1 (learn): Hold out whole genres or story sets during evaluation as a negative control, so the parser and readers can be shown not to rely on topic-specific lexical cues.
- I2 (tree): Before hand-pruning the perceptron parser's feature templates on linguistic grounds, compare against the full template set to see what the pruning actually costs.
- I3 (tree): Rank the perceptron parser's features by information gain and sweep the cutoff to find a smaller, faster model without losing LAS.
- I4 (learn): When upsampling rare constructions in silver training data, report gains on an out-of-domain split as well, so in-domain inflation is caught.
- I5 (tokens): Systematic tagger or lemmatizer failures on learner English could be logged as features that flag non-native input, instead of only being corrected away.
📚 Shelves 7The field of science this work belongs to (OpenAlex fields).Computer Science · 9,086 worksArtificial Intelligence · 8,889 worksArts and Humanities · 9,296 worksLanguage and Linguistics · 9,206 worksPsychology · 798 worksExperimental and Cognitive Psychology · 463 worksSignal Processing · 213 works
🧭 Topics 1Research subjects and languages the work is about.English · 1,373 works
Cite
Cite as Sowmya Vajjala and Ziwei Zhou. 2018. The Relevance of Text and Speech Features in Automatic Non-native English Accent Identification. arXiv:1804.05689.
@misc{vajjala2018relevance,
title = {{The Relevance of Text and Speech Features in Automatic Non-native English Accent Identification}},
author = {Sowmya Vajjala and Ziwei Zhou},
year = {2018},
doi = {10.48550/arxiv.1804.05689},
eprint = {1804.05689},
archivePrefix = {arXiv},
url = {https://doi.org/10.48550/arxiv.1804.05689}
}References
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