Participants spoke sentences while their neural activity was recorded. The acoustic speech was associated with motor movement which was in turn associated with

Participants spoke sentences while their neural activity was recorded. The acoustic speech was associated with motor movement which was in turn associated with learned neural patterns. As such the final result is a multi-stage model which can translate from patient specific (at a minimum in the sense of electrode configuration) neural activity into audio. All neural activity (from what I saw in the paper) is neural activity while the individual is reading sentences out loud.