Let us imagine a situation: a listener seated in a concert hall witnesses a performance by a trumpet player (standing on the stage) of a sequence of four quarter-notes, with the pitches of B[flat ]3–A3–C4–B3. The listener chooses to ignore the immediate physical surroundings and hears one of the following: (i) four trumpet sounds equally spaced in time, (ii) a sequence of intervals – minor second, minor third, minor second, (iii) an instance of set 4-1, (iv) a motive referring to the name of BACH. The `web of interpretants' (term from Nattiez 1987/1990) surrounding a simple musical fact is already quite dense, even though we have only considered its aspects relating to pitch, pitch class and pitch notation (representation by letters). What if the performer's gestures, the facial expressions, the direction of the bell of the instrument became important? Might one say, then, that the music has become theatre?