I believe that used to be called "tone deafness"? While training can help, there are definitely some people who just can't distinguish musical tones! I'm fortunate enough to be on the other end, with absolute pitch, but most people are somewhere in between in varying degrees. The absolute pitch can be very annoying, too, when musicians get the slightest bit off-key!

Then there was General US Grant in the Civil War, who claimed he knew only two tunes. One was "Yankee Doodle"; the other wan't. Bands playing "Rally Round the Flag" and other of the many patriotic Union songs got waved away from his camp.

Anyway, I sincerely hope that the OP and his friends will seriously consider separate earphones for everyone!