Why do we often associate “higher” sounding vowels (E, A, I) with sharp edges and “lower” sounding vowels (O, U) with round/dull/circular edges?

Question

A wiki on the topic https://en.m.wikipedia.org/wiki/Bouba/kiki_effect

In: Other

Answer 1

To quote the researchers in the source of the link you included:

“The Kiki-Bouba effect corresponds to a sound-vision synaesthesia, probably between the tone of vowels and the vertical or horizontal aspect of figures.”

Essentially, in some humans, perceiving something with one sense will cause them to perceive something with another (e.g. some people who hear certain musical notes will perceive colours corresponding to those notes). It seems as though we are hardwired to make connections between different types of stimuli. In that experiment, it showed we associate rounder objects with longer, ‘softer’ noises (b, p, o, etc.) and sharper objects with noises that are more short and ‘hard’ (k, t, e, etc.).