When AVSR Meets Video Conferencing: Dataset, Degradation, and the Hidden Mechanism Behind Performance Collapse
Organizations: Key Laboratory of Aerospace Information Security and Trusted Computing, Ministry of Education · School of Cyber Science and Engineering, Wuhan University · Tsinghua University
Abstract
Audio-Visual Speech Recognition (AVSR) has achieved remarkable progress in offline conditions, yet its robustness in real-world video conferencing (VC) remains largely unexplored. This paper presents the first systematic evaluation of state-of-the-art AVSR models across mainstream VC platforms, revealing severe performance degradation caused by transmission distortions and spontaneous human hyper-expression. To address this gap, we construct MLD-VC, the first multimodal dataset tailored for VC, comprising 31 speakers, 22.79 hours of audio-visual data, and explicit use of the Lombard effect to enhance human hyper-expression. Through comprehensive analysis, we find that speech enhancement algorithms are the primary source of distribution shift, which alters the first and second formants of audio. Interestingly, we find that the distribution shift induced by the Lombard effect closely resembles that introduced by speech enhancement, which explains why models trained on Lombard data exhibit greater robustness in VC. Fine-tuning AVSR models on MLD-VC mitigates this issue, achieving an average 17.5% reduction in CER across several VC platforms. Our findings and dataset provide a foundation for developing more robust and generalizable AVSR systems in real-world video conferencing. MLD-VC is available at https://huggingface.co/datasets/nccm2p2/MLD-VC.
Figures & tables
| Model | Dataset | Modal | Language | Platform | WER(%)↓ | WER(%)↓ | CER(%)↓ | CER(%)↓ |
|---|---|---|---|---|---|---|---|---|
| mWhisper-Flamingo [ 30 ] | LRS3 [ 31 ] | A | En | Offline | 0.68 | |||
| Zoom | 10.38 | 9.70 | ||||||
| Lark | 19.55 | 18.87 | ||||||
| Tencent Meeting | 11.89 | 11.21 | ||||||
| AV | En | Offline | 0.73 | |||||
| Zoom | 9.22 | 8.49 |
| Dataset | Speakers | Duration(h) | Language | VC Num | Year |
|---|---|---|---|---|---|
| Lombard-Grid | 54 | 3.81 | En | 2018 | |
| RoomReader | 118 | 8 | En | 1 | 2022 |
| MLD-VC (Ours) | 31 | 22.79 | En & Zh | 4 | 2025 |
| Acoustic Feature | Platform | ||||
|---|---|---|---|---|---|
| Offline | Tencent Meeting | Lark | DingTalk | Zoom | |
| F0 ( Plain ) | 37.28 | 37.66 | 37.51 | 37.66 | 37.39 |
| F0 ( Lombard ) | 37.58 | 37.85 | 37.62 | 37.64 | 37.55 |
| F1 ( Plain ) | 606.90 | 674.43 | 704.19 | 774.61 | 687.88 |
| F1 ( Lombard ) | 660.06 | 756.11 | 770.17 | 825.44 | 712.73 |
| F2 ( Plain ) | 1655.66 | 1680.78 | 1727.37 | 1783.51 | 1727.45 |
| Test Dataset | Platform | Finetune | CER(%)↓ | Reduction(%) |
|---|---|---|---|---|
| Chinese-Lips [ 32 ] | Tencent Meeting | × | 10.97 | |
| Tencent Meeting | ✓ | 9.65 | 12.0 | |
| Lark | × | 18.53 | ||
| Lark | ✓ | 13.64 | 26.4 | |
| Zoom | × | 9.22 | ||
| Zoom | ✓ | 7.93 | 14.0 |
| Online | Hyper-expression | Tencent Meeting | Lark | Zoom |
|---|---|---|---|---|
| ✓ | ✓ | 9.65 | 13.64 | 7.93 |
| × | ✓ | 10.15 | 15.52 | 10.53 |
| ✓ | × | 10.01 | 14.48 | 9.61 |
| Name | Verb | Classifier | Adjective | Noun |
|---|---|---|---|---|
| 旭峰 (Xufeng) | 买 (Mai) | 零个 (Lingge) | 大 (Da) | 沙发 (Shafa) |
| 青木 (Qingmu) | 乘 (Cheng) | 一架 (Yijia) | 小 (Xiao) | 飞机 (Feiji) |
| 林俊 (Linjun) | 坐 (Zuo) | 两只 (Liangzhi) | 旧 (Jiu) | 火车 (Huoche) |
| 建树 (Jianshu) | 去 (Qu) | 三条 (Santiao) | 快 (Man) | 菠萝 (Boluo) |
| 郭浩 (Guohao) | 拿 (Na) | 四段 (Siduan) | 慢 (Man) | 枕头 (Zhentou) |
| 南月 (Nanyue) | 养 (Yang) | 五棵 (Wuke) | 新 (Xin) | 床 (Chuang) |
| Visual Feature | Platform | ||||
|---|---|---|---|---|---|
| Offline | Tencent Meeting | Lark | DingTalk | Zoom | |
| Lip Width ( clean ) | 0.73 | 0.74 | 0.74 | 0.74 | 0.75 |
| Lip Width ( 80 dB ) | 0.74 | 0.74 | 0.74 | 0.74 | 0.75 |
| Lip Height ( clean ) | 0.29 | 0.28 | 0.28 | 0.29 | 0.28 |
| Lip Height ( 80 dB ) | 0.27 | 0.26 | 0.26 | 0.27 | 0.27 |
| Lip Roundness ( clean ) | 0.41 | 0.40 | 0.40 | 0.41 | 0.37 |
Audio-Visual Speech Recognition
Audio-visual speech recognition combines speech audio and visible mouth movements to transcribe words, especially when sound is noisy or incomplete.
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