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VocalRep: Structure-Aware Vocal Representations for Multimodal Generation

Paper · 2026 · Da Shen, Zhenqiang Weng, Tianyu Liu et al.

Summary

Generative pipelines such as singing voice conversion (SVC) and lip-sync driven by audio usually get their vocal input from music source separation (MSS). Common separators, however, merge the lead singer and backing harmonies into one vocal stem and are tuned for SDR-style reconstruction. The authors argue that this mixing causes pitch jitter and blurred phoneme cues downstream, even when SDR looks good.

They introduce VocalRep, which splits a mix into three stems: lead, harmony and instrument. Its backbone is a Band-Roformer modulated by a song-level singer identity vector. Training adds two ranking-based discriminative critics. One judges how well the lead fits its instrumental context, and the other models lead–harmony dominance. Neither critic runs at inference, and no pitch or symbolic labels are required.

The system was tested on separation benchmarks and through several SVC and lip-sync systems. VocalRep is competitive on separation scores, but its main gain is in intelligibility, pitch stability and sync quality. The work suggests that downstream generation quality is a better yardstick for separators than reconstruction metrics.

Key points

  • Identity conditioning: the Band-Roformer transformer is conditioned via FiLM on a CAM++ speaker embedding.
    • During training, 20 embeddings from random ground-truth lead segments are averaged, and the vector is dropped with probability 0.5.
    • At inference, sliding-window embeddings from the mixture are spectrally clustered, and the centroid of the dominant cluster serves as the song-level anchor.
  • Baselines: MelBand-Roformer, Band-Roformer, MDX23C and SCNet Large, each also in a "stem-reconfigured" variant.
  • Downstream evaluation:
    • Lip-sync was tested with Wav2Lip, EchoMimic and Hallo2 on the Multisong and PHV-40 datasets, measured by Sync-D and Sync-C.
    • VocalRep reports the best relative lip-sync results.
  • Ablation (PHV-40):
    • Lead/harmony SDR rises from 6.94/3.49 dB (base) to 7.29/4.05 dB (full model with ID correction).
    • RVC F0PCC rises from 88.15% to 90.81%.
    • The dual-scorer critics alone cut CER from 46.44% to 41.95%.
  • Limitations and release:
    • VocalRep scores slightly below specialized models on 2-stem benchmarks because errors accumulate when stems are separated and then summed.
    • The single-singer assumption breaks down for duets.
    • Code is on GitHub (Zhenqiang-Weng/music_source_separation).

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

 Fields, topics and concepts

Cite

Cite as Da Shen, Zhenqiang Weng, Tianyu Liu, Gongyu Chen, Runhua Shi, Jiahui Chen, Chaofan Ding, Wei-Qiang Zhang and Zihao Chen. 2026. VocalRep: Structure-Aware Vocal Representations for Multimodal Generation. Findings of the Association for Computational Linguistics: ACL 2026.

The paper itself, not this page. BibTeX from the library's record of the work. DOI 10.18653/v1/2026.findings-acl.1785

@inproceedings{shen2026vocalrep,
  title = {{VocalRep: Structure-Aware Vocal Representations for Multimodal Generation}},
  author = {Da Shen, Zhenqiang Weng, Tianyu Liu, Gongyu Chen, Runhua Shi, Jiahui Chen, Chaofan Ding, Wei-Qiang Zhang and Zihao Chen},
  booktitle = {Findings of the Association for Computational Linguistics: ACL 2026},
  year = {2026},
  doi = {10.18653/v1/2026.findings-acl.1785},
  url = {https://doi.org/10.18653/v1/2026.findings-acl.1785}
}

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