Shreeram Suresh Chandra

arXiv2026

Brain2Speech-Net: Intelligible, Real-Time Brain-to-Speech Synthesis Without Text Decoding

The loss of speech limits communication for individuals with paralysis. Restoring speech by synthesizing it directly from neural activity is challenging: intracortical data are scarce and lack aligned targets, so most systems rely on cascaded neural-to-text-to-speech pipelines that add latency and propagate errors. We present Brain2Speech-Net, among the first single-stage frameworks to remain intelligible under limited data while removing intermediate text decoding. A differentiable phoneme bottleneck preserves linguistic structure without explicit text decoding. A lightweight deep-HMM aligner then maps this bottleneck to contextual phoneme representations in a TTS latent space. It learns monotonic alignment between neural recordings and phoneme segments without frame-level supervision, inheriting strong acoustic priors for data-efficient training. On an intracortical dataset, Brain2Speech-Net achieves strong intelligibility in objective and listening tests while running faster than real time. Unlike cascaded systems that incur high latency and direct speech-unit models that lack intelligibility, it delivers both intelligible and real-time speech.

eess.AS↗

arXiv2026

Cleaner Speech, Weaker Generalization: Revisiting Pitt-Derived Benchmarks for Alzheimer's Disease Detection

Speech-based Alzheimer's disease (AD) detection increasingly relies on speech-enhanced and curated versions of the Pitt Corpus, where speech enhancement, sample selection, and demographic balancing are often treated as beneficial preprocessing steps. However, whether these transformations improve real-world AD detection or instead affect model generalization and prediction behavior remains unclear. In this work, we revisit the role of speech preprocessing and dataset curation across widely used benchmarks for speech-based AD detection. We evaluate the speech quality of different datasets, the cross-dataset generalization of multiple deep learning models under matched and mismatched enhancement settings, and the behavior of several recent large audio-language models (LALMs). Experimental results show that across multiple supervised speech models, speech-enhanced datasets often improve in-domain performance while reducing robustness in cross-domain evaluation. Matched enhancement between training and test data alleviates, but does not eliminate, this degradation. LALMs show a similar sensitivity: enhanced datasets induce stronger class imbalance and prediction shifts than unprocessed data. These results suggest that speech preprocessing and dataset curation can substantially influence downstream AD detection behavior, indicating that ``cleaner'' speech datasets are not necessarily more reliable for real-world AD detection.

cs.SD↗