I dont think medium is the word you wanted. What is it about the "medium" (which I am assuming is 'air' since it is a spoken language) of piraha language that has shaped/created a language without numbers/colors despite the fact that english has colors and numbers?
I've heard the argument that some of these channels may be influenced by the jungle environment (whistled language elsewhere is frequently used outdoors because whistles carry farther). And I think whistled or musical speech is likelier to occur in tonal languages with a simple phonology (Pirahã's is very simple and very tonal). Dan Everett's claim was that a cultural avoidance of indirect references influenced the grammar of Pirahã (to put it crudely).
