Formants & Speech Perception

[CTB1954]

My understanding of speech perception is that the brain takes the ratio of
the formants for phoneme extraction.  The ratio is fairly constant within
a population of different pitched (male, female & children) within a given
dialect.
You have an excellent facility over in the Netherlands where you can get
more detailed information.  It is called the Institute for Perception
Research.  I regretfully don't know the city.  Good luck!