English: Supplementary Video S1 illustrates the participant's performance with the BCI during consecutive five trials in a real-time feedback session. Each trial starts with the computer playing the word “listen” followed by the utterance to be produced (a vowel-to-vowel utterance starting at the vowel UH and moving to the target vowel for that trial). The computer then plays the word “speak”, which is followed by the subject's attempt to produce the utterance with the BCI, including the synthesizer sound output and corresponding formant plane representation. A successful attempt occurs if the cursor reaches the target vowel location (indicated in green) within six seconds.