I focus on the relationship between sensory perceptions, as it is reflected in language. I provide a comprehensive theoretical framework, which includes an overview of the latest neuroscientific research on the connection between the two main sensorial modalities (in humans), sight and hearing. I then offer a crosslinguistic perspective on the verbalization of this relationship, both in synchrony and diachrony. By showing that many words that denote a visual impression stem from lexical roots expressing an acoustic sensation, we propose a closer evaluation of several Indo‑European etymological families related to the semantic field of ‘brightness’. I observe that many lexical roots that have been artificially separated into two or more homonymic stems because of an apparent semantic incompatibility actually go back to a common origin, namely the verbalization of a sound, and have followed recurrent patterns in their semantic evolution towards the designation of a luminous phenomenon. This approach could provide new insights in the role played by synaesthesia in language evolution.