When is sound paired with meaning during language production? The exploration of inner speech offers a unique opportunity to approach this fundamental question, allowing a general reflection on the architecture of human language structure and its evolution. Recent experiments based on awake surgery techniques show that during language production the code exploited by neurons contains acoustic information even in non-acoustic areas such as Broca’s area and even during inner speech (Magrassi et al. 2014), that is without externalization (Chomsky 2013, Friederici et al. 2018). After illustrating these results and their implications I will highlight the surprising convergence with an independent proposal predicting these findings from the point of view of a purely formal theory aiming at explaining some apparently idiosyncratic morphological properties of the English verb system (Kayne 2016). Further speculation on Merge and clause structure will be addressed according to the results described here (Moro 2004).