Introduction

The author explores sound synthesis research. And his computer music pieces are dependent on these technologies. This attitude comes originaly from Musique Concrete.

Outline of music pieces

1. Shizuku no Kuzushi (Variation of Water Drops) Program note
   Aug. 4, 1991. Computer Music Independent Concert
   [Kobe XEBEC Hall] Premiered.
   Sep. 10, 1993.ICMC'93 (International Computer Music Conference)
   [Waseda University, Ibuka Hall]
   　　　Yoshinao Shiraki(Violin)
   　　　Naotoshi osaka(Software and Computer operation)

   Nango ``YayaYa'' Program note

   Feb. 11, 1993. Organized by Information Processing Society of Japan, Special Interest Group on Music, co-organized by Japan Contemporary Music Association

   ``Computer Music II''[Ginza Juujiya Hall]premiered

   Hiroko Oh-ide(Soprano)

   Yoshinao Shiraki(Violin)

   Naotoshi Osaka(Software and Computer operation)

   Masokagakmi Program note

   Nov. 6, 1994. Organized by Japan Computer Music Association, ``Computer Music Today I''

   [Kobe XEBEC Hall]premiered

   　　　Setsu Inoue (Soprano)

   Sep. 3, 1995. 　MUSIANA95[Louisiana Museum, Denmark]

   Hanne Andersen(Soprano)

   Naotoshi osaka(Software and Computer operation)

   Prosody++ Program note

   1995.9.3　 MUSIANA95（Japan Today)[Louisiana Museum, Denmark]Premiered.

   Norio Sato(Cond.)

   Yukihiko Nishizawa(Flute)

   Mitsuko Ishii(Violin)

   Yo-hei Matsuoka(Violoncello)

   Keiko Harada(Piano)

   Naotoshi osaka(Software and Computer operation)

   Mirror Stone Program note

   July 13, 1996. Organized by Japan Computer Music Association, ``Computer Music Today II''

   [Kobe Xebec Hall]Premiered

   　　　Ayako Nishikawa(Flute)

   Naotoshi Osaka(Software and Computer Operation)

1. Shizuku no Kuzushi
   • Program Note
     Naotoshi Osaka
     Computer operator: Naotoshi Osaka
     Violin: Yoshinao Shiraki
     The piece inherits the concept of music concrete. Besides traditional pitch- oriented musical system, the composer believes that a large part of a musical system lies in the timbre of a sound. ``shizuku'' in the title means a water drop, which is the basic sound material throughout the whole piece. ``kuzushi'' means variation, and the whole piece explores possible variation int the raw water drop sound. As a whole, the title represents the composer's wish that the piece acquire some sort of order, even if it only consists of timber variation. The piece is divided into seven sections, each of which is named after a syllable in the title: ``shi'',``zu'', etc. The piece was premiered at Xebec hall, Kobe, in ``Computer Music Independent Concert'', in August 1991. Several digital signal processing techniques are used to make the variations in the water drop sound: time variant digital filters, spectrum foldover distortion, phase distortion caused by manipulation in the Z domain after Hilbert transform of a sound, etc. The processing software is named ``Otkinshi''; it runs on a NeXT computer. The software details of were presented at ICMC'92.

2. Nango ``YayaYa'' (Japanese; English version not ready)
   • Program Note
     

3. Masokagami
   • Program Note
     The word Masokagami represents a limpid mirror used in religious services in ancient Japan. It also contains the words for `shine' and `image's. In music or acoustic signal, it is very important to repeat or overlap the same information over and over again. In the counterpoint, which is one of the fundamental composition techniques, musical order is produced by using the repetition of theme's variation, such as inversion, retrograde etc. In the meantime, the acoustic signal gives us different impressions in relation to the delay time, such as timbre variation, reverberation, and echo.

     The concept of ``repeating the same information" is important not only in music, but also in visual art and even in daily life. Various mirrors are tools to reflect or repeat rays. By choosing a mirror as the theme of a piece, the composer tries to evoke a double effect, conveying the impression of the mirror and musical unification. Lyric texts are referred to ``Man'yoshu'', which is an eighth century style of poetry, consisting mainly of {\it tanka} poems, the Japanese ode of 31 (5+7+5+7+7) syllables. Three tankas are selected because of their relevance to a mirror,

   masokagami:
   • No. 2810 Otonomi o Kikiteya kohim masokagami meni tadani ahite kohimakumo ooku.
   • No. 2811 konokoto o kikamto aram masokagami tereru tsukiyomo yaminomini mitsu.
   • No. 2634 Satotoomi kohiwabinikeri masokagami omokagesarazu yumeni miekoso.
   In this performance, MAX and Otkinshi are running on a Next computer with ISPW.

4. Prosody++ for Flulte, Violin, Violincello, Piano, and NeXT
   • Program Note
     Naotoshi Osaka
     Prosody, or the musical structure of speech such as its intonation and rhythm, can -- with regard to emotion, modality and turn-taking in conversation-- convey as much as or more information than phonemes do. This piece is aimed at finding instrumental role of prosody in order to cope with real musical instruments. For this purpose, voice quality, pitch, and intonation modification is done. This procedure is, so to say, musically sophisticated prosody synthesis. On the contrary, instruments try to follow the prosodic structure of speech. All the speeches recorded are from actual Japanese dialogue, and the speech is digitally processed. Performance is done using ``Otkinshi", which is sound generation and performance software on NeXT computer.

5. ``Mirror Stone'' for flute and computer
   • Program Note
     The composer has been creating a series of music under the theme of mirrors. This piece refers to the story ``Mirror Stone'' by R. Seymour. A mirror reflects an exact image of an object. But it is a reverse image, and it gives the impression that the world in a mirror is completely different, even though it resembles the real world on the surface. This story set up the ``mirror stone'' as a subject which perfectly reflects things even the inner world of a human being. It also treats the world in a mirror as a mysterious and magical one. Although such an interpretation of a mirror is not special in stories, the aim of the piece is to express such a mysterious and magical atmosphere using sounds.

   • Technical note
     A timbre control technique in which a timbre of an original instrument is gradually changed to a different timbre is used here. This technique is called ``morphing''. The morphing technique is now widely known in computer graphics, but is still under study in sound synthesis. In this piece, modification of a flute timbre is the main concern, and morphing is widely used all over in the piece.

     Two characteristics of sound synthesis and music performance are as follows:

     1. Real time sound signal processing using NeXT + ISPW and MAX.
     2. Timbre interpolation technique by sound morphing.
     The are two types of sound morphing: one done by a performer, regarded as an advanced player technique, and the other, an off line signal processing technique done by a computer. This piece combines the two types. Also, reverberation, pitch shift and various effects are implemented by MAX.
     References
     

     [Seymour 1988] Richard Seymour, Michael Palin and Alan Lee, ``The Mirrorstone,'' Jonathan Cape Ltd, London, 1986.