Photoskia is a work-in-progress for solo tape with a section that is based on the acoustic properties of the vowels [u], [a], and [i], which are treated as a harmonic progression. The term harmonic progression, when used in this context refers not to a progression of chords that requires a resolution of dissonance, but to what is perceived as a gradual transition in timbre from the low, grave dark sound of [u] to the high, acute, bright sound of [i]. Where in a more traditional context harmonic progressions are ordered to create tension and release, this progression creates a slow evolution in frequency structure that does not require resolution.

The sound sources for the tape are acoustic instruments: violin, contrabass, baritone saxophone, soprano voice, and tenor voice. The sound colour of individual instruments orchestrates the vowels, composing the characteristic timbre within each vowel sound. The acoustic sounds are not electronically modified – changes in timbre result from the layering of sounds into a single entity, or vowel sound.

I did a spectral analysis of each vowel sound with spectrograms, tracing the formant trajectory from [u] to [i]. A series of up to twenty-one harmonics was constructed on the fundamental pitch of each vowel. In this case the pitches B, Bb and C within the range of each instrument. Each pitch was then tuned to just intonation, or the overtone series, with the use of the tape-speed variation control of the tape recorder. The tuning of each individual harmonic to an acoustically true interval helps to fuse each individual timbre into what is heard as a single sound. Timbral coherence is achieved through gradual shifts in timbre created by shifting vowel qualities and orchestration.

Photoskia is a Greek word meaning show / light, and refers to the qualities of spectral elements in the piece.

Listen (excerpt)

Formant Trajectory, Photoskia