Figure 1.

Overview of the closed-loop speech synthesizer. (A) Neural activity is acquired from a subset of 64 electrodes (highlighted in orange) from two 8 × 8 ECoG electrode arrays covering sensorimotor areas for face and tongue, and for upper limb regions. (B) The closed-loop speech synthesizer extracts high-gamma features to reveal speech-related neural correlates of attempted speech production and propagates each frame to a neural voice activity detection (nVAD) model (C) that identifies and extracts speech segments (D). When the participant finishes speaking a word, the nVAD model forwards the high-gamma activity of the whole extracted sequence to a bidirectional decoding model (E) which estimates acoustic features (F) that can be transformed into an acoustic speech signal. (G) The synthesized speech is played back as acoustic feedback.