Seeing the color red or experiencing the taste of coffee, for example, are subjective qualitative characters of sensation; we can't fully explain how they feel. Qualia is the philosophical term for these subject, non-transferable "what is it like" experiences.
The musical narrative of this piece implies a "sensation" of the discourse instead of an assertion. The pianist is confronted with "Qualia-inducing" commentary printed on the score. Perhaps those fleeting experiences of the pianist could fly around the hall and be carried along with the music. Perhaps we, in the audience, could experience them exactly in the same way.