# BA-MoE: Boundary-Aware Mixture-of-Experts Adapter for Code-Switching Speech Recognition

arXiv: https://arxiv.org/abs/2310.02629 · HTML: https://mlsanity.com/paper/2310.02629/

## Key facts

- Cited by 9 papers in the map (data through 14 Oct 2026).
- Placed in Multimodal MoE models, one of 12 directions in Mixture-of-experts.
- Builds on 22 of its 31 references that are in the map.
- First posted on arXiv 4 Oct 2023.

## Placed in

- Mixture-of-experts / [Multimodal MoE models](https://mlsanity.com/moe/multimodal-moe-models/)

## Builds on (most cited first, 22 of 22)

- [Attention Is All You Need](https://mlsanity.com/paper/1706.03762/) (2017)
- [Deep Residual Learning for Image Recognition](https://mlsanity.com/paper/1512.03385/) (2015)
- [Conformer: Convolution-augmented Transformer for Speech Recognition](https://mlsanity.com/paper/2005.08100/) (2020)
- [Attention-Based Models for Speech Recognition](https://mlsanity.com/paper/1506.07503/) (2015)
- [A Structured Self-attentive Sentence Embedding](https://mlsanity.com/paper/1703.03130/) (2017)
- [End-to-End Speech Recognition: A Survey](https://mlsanity.com/paper/2303.03329/) (2023)
- [CIF: Continuous Integrate-and-Fire for End-to-End Speech Recognition](https://mlsanity.com/paper/1905.11235/) (2019)
- [A Survey of Code-switched Speech and Language Processing](https://mlsanity.com/paper/1904.00784/) (2019)
- [The ASRU 2019 Mandarin-English Code-Switching Speech Recognition Challenge: Open Datasets, Tracks, Methods and Results](https://mlsanity.com/paper/2007.05916/) (2020)
- [Exploiting Adapters for Cross-lingual Low-resource Speech Recognition](https://mlsanity.com/paper/2105.11905/) (2021)
- [Multi-Encoder-Decoder Transformer for Code-Switching Speech Recognition](https://mlsanity.com/paper/2006.10414/) (2020)
- [Transformer-Transducers for Code-Switched Speech Recognition](https://mlsanity.com/paper/2011.15023/) (2020)
- [LAE: Language-Aware Encoder for Monolingual and Multilingual ASR](https://mlsanity.com/paper/2206.02093/) (2022)
- [Language-specific Characteristic Assistance for Code-switching Speech Recognition](https://mlsanity.com/paper/2206.14580/) (2022)
- [Joint Modeling of Code-Switched and Monolingual ASR via Conditional Factorization](https://mlsanity.com/paper/2111.15016/) (2021)
- [Towards Zero-Shot Code-Switched Speech Recognition](https://mlsanity.com/paper/2211.01458/) (2022)
- [Boundary and Context Aware Training for CIF-based Non-Autoregressive End-to-end ASR](https://mlsanity.com/paper/2104.04702/) (2021)
- [Study of Semi-supervised Approaches to Improving English-Mandarin Code-Switching Speech Recognition](https://mlsanity.com/paper/1806.06200/) (2018)
- [Reducing language context confusion for end-to-end code-switching automatic speech recognition](https://mlsanity.com/paper/2201.12155/) (2022)
- [Internal Language Model Estimation based Language Model Fusion for Cross-Domain Code-Switching Speech Recognition](https://mlsanity.com/paper/2207.04176/) (2022)
- [Monolingual Recognizers Fusion for Code-switching Speech Recognition](https://mlsanity.com/paper/2211.01046/) (2022)
- [Language-specific Acoustic Boundary Learning for Mandarin-English Code-switching Speech Recognition](https://mlsanity.com/paper/2306.05279/) (2023)

## Built on by (most cited first, 9 of 9)

- [Boosting Code-Switching ASR with Mixture of Experts Enhanced Speech-Conditioned LLM](https://mlsanity.com/paper/2409.15905/) (2024)
- [SC-MoE: Switch Conformer Mixture of Experts for Unified Streaming and Non-streaming Code-Switching ASR](https://mlsanity.com/paper/2406.18021/) (2024)
- [CAMEL: Cross-Attention Enhanced Mixture-of-Experts and Language Bias for Code-Switching Speech Recognition](https://mlsanity.com/paper/2412.12760/) (2024)
- [Improving Zero-Shot Chinese-English Code-Switching ASR with kNN-CTC and Gated Monolingual Datastores](https://mlsanity.com/paper/2406.03814/) (2024)
- [Dynamic Language Group-Based MoE: Enhancing Code-Switching Speech Recognition with Hierarchical Routing](https://mlsanity.com/paper/2407.18581/) (2024)
- [XCB: an effective contextual biasing approach to bias cross-lingual phrases in speech recognition](https://mlsanity.com/paper/2408.10524/) (2024)
- [UME: Upcycling Mixture-of-Experts for Scalable and Efficient Automatic Speech Recognition](https://mlsanity.com/paper/2412.17507/) (2024)
- [On-the-fly Routing for Zero-shot MoE Speaker Adaptation of Speech Foundation Models for Dysarthric Speech Recognition](https://mlsanity.com/paper/2505.22072/) (2025)
- [LLM-HB: Language-Aware LLM-Guided Hotword Biasing for Code-Switching ASR](https://mlsanity.com/paper/2610.16579/) (2026)

## Abstract (arXiv)

Mixture-of-experts based models, which use language experts to extract language-specific representations effectively, have been well applied in code-switching automatic speech recognition. However, there is still substantial space to improve as similar pronunciation across languages may result in ineffective multi-language modeling and inaccurate language boundary estimation. To eliminate these drawbacks, we propose a cross-layer language adapter and a boundary-aware training method, namely Boundary-Aware Mixture-of-Experts (BA-MoE). Specifically, we introduce language-specific adapters to separate language-specific representations and a unified gating layer to fuse representations within each encoder layer. Second, we compute language adaptation loss of the mean output of each language-specific adapter to improve the adapter module's language-specific representation learning. Besides, we utilize a boundary-aware predictor to learn boundary representations for dealing with language boundary confusion. Our approach achieves significant performance improvement, reducing the mixture error rate by 16.55% compared to the baseline on the ASRU 2019 Mandarin-English code-switching challenge dataset.