Familiarity with a composer's style and esthetics is essential in preparation of music from any period. How can we go about learning these essentials when faced with music of a composer who is new to us?
First, research and familiarize yourself with the composer's other works, and perhaps more interestingly, find his/her sources of inspiration. These sources may be musical (traditional Japanese music, in Toru Takemitsu's case) or non-musical (Edgar Varèse and Iannis Xenakis were both inspired by architecture). Here are some specific suggestions:
Luciano Berio, Sequenza no. 1: listen to the Sequenza no. 3 for voice (even though the vocal Sequenza post-dates that of the flute). Listen to a recording of Cathy Berberian for whom the piece was written (recorded on the Wergo label), or Luisa Castellani (Deutsche Gramophon). If you ever have a chance to hear Ms. Castellani perform this piece live, jump at it, she does a stunning job from memory.
Edgar Varèse, Density 21.5: listen to the woodwind solos in the ensemble pieces: Intgrales, Hyperprism and Octandre. Poeme Electronique, his last finished work, I believe, shows how he realized his concept of blocks of sound electronically. This piece, architecturally inspired by LeCorbusier, seems to be a culmination of his ideals.
Toru Takemitsu, Voice or Itinérant: Listen to some traditional shakuhachi playing as well as music from Noh theater, although Takemitsu only later in his career composed with traditional Japanese elements and for Japanese instruments. In November Steps, a concerto for solo biwa and shakuhachi, you can hear how he combines these traditional instruments with modern orchestration. The films for which he wrote music show how he valued the notion of timing and movement.
Kazuo Fukushima, Mei, Shun-San, Requiem: Fukushima was not a terribly prolific composer. Although he is still alive at the time of this writing, he seems to have stopped composing at the end of the nineteen-sixties and devoted himself to full-time teaching. To understand the esthetic of his works, one should be familiar with the sounds of traditional Japanese Noh Theater, its flutes, drums and chorus, and the experimental style of Western music of the sixties with its early forays into the use of extended techniques and graphic notation.
Salvatore Sciarrino, Opera per flauto vol. 1 & 2 : Each piece in this two volume set exists in its own sound universe through the exploitation of a particular set of extended effects. For me it was useful to hear how he translates some of the same effects to other instruments such as the clarinet solo Let me die before I wake. His ensemble pieces Esplorazione del Bianco and Introduzione all'oscuro are good examples of how he uses particular instrumental effects to create atmosphere.
Find the composer's sources of inspiration by reading biographical information or reading his/her own writings, often easily found in libraries or the internet. If the composer has little internet presence one can also try:
• searching the directories of national composer's unions (ASCAP in the US)
• sending inquiries through the composer's publisher
• sending inquiries to the CD or record label on which that composer is recorded
Information about lesser-known composers may be scant, or recordings of their works may not be available. In this case, don't despair, ask around. Use your own resources, knowledge of different styles and the knowledge of colleagues or friends. Ask the advice of other composers. If they are amenable, offer to play for them. Sometimes it has helped me to play for someone who is trained to listen to form.