Master Blue said... the heart looked the same on the outside, but was different for others on the inside...

[He frowns. It looks like... he's listening?]

I don't know... I've never heard it before. It sounds like... a bell? No... not a bell... [He doesn't know how to make the sound, so he hums it:] Mm. [A one or two second pause.] Mm. [Another one or two second pause.] Mm.