One Head, Three Transcripts: A Controlled Oracle-to-ASR Audit of Bangla Speech–Text Sentiment Analysis

Md Raihan, Nilam Rajak, Kuntal Ghosh, Sathyanarayanan Dhorali


Abstract
Speech sentiment systems are routinely benchmarked with gold transcripts, but a deployed cascade must read whatever its recognizer produces. We audit that gap on BanglaMUSE, a Bangla read-speech sentiment corpus, using sentence-grouped cross-validation and a controlled substitution design in which one trained classifier is evaluated three times while only the test-time transcript changes. Replacing gold transcripts with ASR output costs 0.109 macro-F1 with Bengali XLS-R CTC and 0.341 with our Whisper large-v3 configuration, a high-error stress case. Retraining the classifier on matched recognizer output recovers 57–81% of the gap, but re-selecting only the decision threshold on ASR validation data, with weights and probabilities unchanged, already recovers 28–49%. Adding the speech embedding improves over ASR text, yet replacing it with acquisition/nuisance features gives a similar gain for gold-trained heads. These features alone predict sentiment at 0.669 macro-F1 (group-permutation null mean 0.495, p = 0.001), and a speech-only classifier that reaches 0.940 falls to 0.621 when both speaker and sentence are unseen. These speech-only and fusion results therefore do not provide clean evidence of prosodic sentiment cues. Low-resource speech–text benchmarks should report oracle and deployable conditions, separate threshold effects from retraining, and test acquisition variables before interpreting audio.
Anthology ID:
2026.mmlow-main.4
Volume:
Proceedings of the Fifth Workshop on Multimodal Machine Learning in Low-resource Languages
Month:
November
Year:
2026
Address:
Hengqin, China
Editors:
Rahul Ponnusamy, Prasanna Kumar Kumaresan, Saranya Rajiakodi, Premjith B, Shunmuga Priya MC, Abirami Murugappan, Jyothish Lal G, Sowmya V, Bharathi Raja Chakravarthi
Venues:
MMLow | WS
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
40–54
Language:
URL:
https://aclanthology.org/2026.mmlow-main.4/
DOI:
Bibkey:
Cite (ACL):
Md Raihan, Nilam Rajak, Kuntal Ghosh, and Sathyanarayanan Dhorali. 2026. One Head, Three Transcripts: A Controlled Oracle-to-ASR Audit of Bangla Speech–Text Sentiment Analysis. In Proceedings of the Fifth Workshop on Multimodal Machine Learning in Low-resource Languages, pages 40–54, Hengqin, China. Association for Computational Linguistics.
Cite (Informal):
One Head, Three Transcripts: A Controlled Oracle-to-ASR Audit of Bangla Speech–Text Sentiment Analysis (Raihan et al., MMLow 2026)
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PDF:
https://aclanthology.org/2026.mmlow-main.4.pdf