Arnold Schoenberg: Pierrot Lunaire Op. 21 (1912) atonality--not bound by traditional tonality that requires the resolution of leading tones, and often lacks any tonal center. Schoenberg also wrote asymmetrical, highly unusual rhythms, and sections or entire pieces of his could be devoid of any clear time signature or consistent beat. In addition, his instrumentation was unusual, which led to future composers experimenting with new instrument combinations rather than just the old standbys (i.e. string quartet, piano trio). One other compositional tool Schoenberg used is seen in the soprano's part: rather than asking the soprano to sing in the typical operatic fashion, he calls for "sprechstimme," which was a rare vocal technique that combined singing and talking. Pierrot Lunaire was only the third time it was ever used, and it was the first piece to call for sprechstimme throughout the entire soprano part. He left instructions on how to do it properly, which helped establish and popularize the technique with other avant-garde musicians.