Well, I think he has a point.
Panel 1: A café. A close-up of Sigma sitting down at the table with a spoonful of cake. He says “Okay, so–”
Panel 2: A close-up of Xi at the other side of the table, with a concentrated look. Sigma (off panel) says “Most people have a favorite color, right?”. Xi says “…yeah…”
Panel 3: Sigma raises an eyebrow and says “Then why don’t people have a favorite pitch?”
Panel 4: Sigma waves his hands, looking excited. He says “I mean, they’re like, the same thing!”
Panel 5: Sigma smiles nervously. He says “Frequencies, right? …Xi?”
Panel 6: Xi holds her head with both hands, resting her elbows on the table. She looks down with big stressed eyes and says “Why do you keep doing this to me”