Here is wikipedia’s article on “cent” and just noticeable difference (JND) - did you look at this already?
“Note that the JND for pitch difference is 5–6 cents. Played separately, the notes may not show an audible difference, but when they are played together, beating may be heard (for example if middle C and a note 10 cents higher are played). At any particular instant, the two waveforms reinforce or cancel each other more or less, depending on their instantaneous phase relationship. A piano tuner may verify tuning accuracy by timing the beats when two strings are sounded at once.”
Steve Parker that looks like a pretty terrific trombone quintet!