One character of this profession has a conversation with Doctor Vigelius accompanied by offstage  celesta and piano, and then dies in Grete's arms after having been haunted by the title phenomenon in a  work by Franz Schreker. In another opera, one of these people sings "Du Venus' Sohn" and, in order to please the richest man in Vienna, makes an agreement with Zerbinetta that he immediately regrets. Sil a,  also a trouser role, is an apprentice of this profession in another work; unlike Ighino, he eventual y leaves for Florence rather than continuing to study this pursuit with the al egedly old-fashioned title character.  That character plies this craft al night long after being visited by nine ghostly masters of this profession, as wel as 
One character of this profession has a conversation with Doctor Vigelius accompanied by offstage  celesta and piano, and then dies in Grete's arms after having been haunted by the title phenomenon in a  work by Franz Schreker. In another opera, one of these people sings "Du Venus' Sohn" and, in order to please the richest man in Vienna, makes an agreement with Zerbinetta that he immediately regrets. Sil a,  also a trouser role, is an apprentice of this profession in another work; unlike Ighino, he eventual y leaves for Florence rather than continuing to study this pursuit with the al egedly old-fashioned title character.  That character plies this craft al night long after being visited by nine ghostly masters of this profession, as wel as his dead wife Lucrezia. For 10 points, name this profession practised by the aforementioned  characters from Der ferne Klang, Ariadne auf Naxos, and the Hans Pfitzner opera Palestrina.
One character of this profession has a conversation with Doctor Vigelius accompanied by offstage  celesta and piano, and then dies in Grete's arms after having been haunted by the title phenomenon in a  work by Franz Schreker.
composers [prompt on "musicians", I guess]