https://www.merriam-webster.com/dictionary/nondiscursive
nondiscursive
non·dis·cur·sive | \ ˌnän-dis-ˈkər-siv \
Definition of nondiscursive
: not of or relating to language or discourse : not discursiveMaking music, while it fulfills many emotional needs, is a nondiscursive enterprise; it doesn’t take place within language.— Randall Butler

And yet, surely, there is ‘discourse’ between the members of the quintet? Personally, I seemed to derive more from Mozart than from most conversations.
I am still thinking about it.Discourse means a narrative I think.Or logical explanation or connection, not just ordinary comversation.And being with a person we may pick up more from their body language.Are they holding a rock in their hand as they glare at you?