Berio explored the frontiers of sound, particularly vocal sound, thanks to his association with Berberian. She was willing and able to produce a remarkable variety of extended techniques with her voice, which she did with the utmost musicianship. But Berberian was also able to win audiences with her superior showmanship. Representative of Berio's vocal writing is Sequenza III for solo voice, which portrays 44 emotional states in seven and a half minutes and includes conventional singing, coughs, sighs, sobs, and a sound Berio called "girl-bird." The work Omaggio a Joyce used Berberian's voice as the source sounds for a tape music piece. The more traditional Folk Songs was a display piece for her facility with languages. Berio's noteworthy, ongoing series of solo instrumental works — many in theSequenza series — have often explored the timbral possbilities of a particular instrument.