Artigo Revisado por pares

Formant Synthesis, Granular Synthesis, and Waveshaping in "Halo, Bells and Voices", Bessell

2007; Perspectives of New Music; Volume: 45; Issue: 1 Linguagem: Inglês

10.1353/pnm.2007.0011

ISSN

2325-7180

Autores

David Bessell,

Tópico(s)

Music and Audio Processing

Resumo

Formant Synthesis, Granular Synthesis, and Waveshaping in Halo, Bells and Voices, Bessell L__7i_ David Bessell This article sets out to demonstrate an approach to composition for the electric guitar based on ideas, sounds, and concepts originating in theworld of musical electronics. In the case ofHalo, Bells and Voices the electric guitar/valve amplifier combination is treated as far as possible as a conventional instrument while the electronic elements are largely represented metaphorically in the piece by the use of extended tech niques. It ishoped that this approach to electronics, combined with the nature of the pitch material used, will contribute to thewidening of the pool of spectral compositional techniques explored to date. It is also the Formant Synthesis, Granular Synthesis, andWaveshaping 237 intention to highlight a possible expanded role for the electric guitar in the context of contemporary artmusic, an area inwhich itspossibilities have been largely under utilized. What is explored in this piece could be characterized as falling somewhere between the improvisational avant garde guitar experimentation of Fred Frith and the more formal approach of concert pieces such as Proenca, by John Buller (1977). The electric guitar was selected as one of a small group of instruments, which might include the Fender Rhodes electric piano and the Clavinet, that sit ambiguously between the electronic and acoustic worlds. The electric guitar in particular has a sound which is almost equally deter mined by acoustic and electronic elements. The realworld vibrations of the strings and the resonance of the body contribute formantswhich are augmented by additional formants resulting from the pickups and ampli fier.The role of the amplifier and speakers isparticularly important in this respect when they are used to add distortion to the sound. Guitar play ers, in the various popular styleswith which the electric guitar is conven tionally associated, often expend a considerable amount of effort on finding the right combination of guitar and amplifier distortion type to achieve an ideal sound, in amanner which can be compared to the elec tronic technique of waveshaping as firstdemonstrated by Risset (1969). This is a technique inwhich awaveform isdeformed by a non-linear dis torting process to generate the desired harmonic character. This tech nique can produce such similar results that it has been used in commercial amplifier modelling software to digitally mimic the non linear characteristics of the overdriven valve distortion which is favored by electric guitar players as a timbre-shaping technique. Although the dual nature of the electric guitar gives it access to the whole range of electronic effects and processes which can be inserted between the guitar and amplifier, itwas decided in the case ofHalo, Bells and Voices to rule out these possibilities to focus attention on themanip ulation of formants and the metaphorical representation of a variety of electronic concepts and sounds. The equipment used was therefore con fined to the "classic" rock set up of Gibson Les Paul guitars andMarshal amplifierswith just foot-pedal controlled volume for convenience. All of the varied sounds used in the piece were achieved by a combination of extended playing techniques and two contrasting levels of amplifier dis tortion (a mild subtle distortion and a more extreme setting similar to the sounds used in the popular "Heavy Metal" genre). Two Fender basses through Fender amplifierswere also used. The piece itselfhas a pitch scheme largely based on spectral analysis of a bell and a voice (Examples 1 and 2). 238 PerspectivesofNew Music example 1: spectral analysis of the bell EXAMPLE 2: TENOR VOICE ANALYSIS (d2) FormantSynthesis, Granular Synthesis, and Waveshaping 239 From this analysis of the bell the following prominent frequencies were derived foruse in the piece. Frequency Nearest Note (rounded to the nearest quarter tone) 678.4 E 1856.7 B\> 2116.9 C 3900.6 B 5010.3 Et 5429.5 E?l 5741.9 FelU frn*Vfc ftiitll M flfiffir.r. iffKfTfirfn iflTiTfiffirfi iLffiffiirifi^' ^ /=====-?p f ---==?p f _==?* _===?J* San to guitar 1 but at the thirteenth position /__=_=-p f*.-j? /_=--?-J? /=-=-=-* Sim to guitar 1 but at the fifteenth position /-?-# /~=-* / ?-* ^- -1? /? -J? "TD Sim to guttar 1 at the fourteenth position ft) With a comer of a second bottle held m...

Referência(s)
Altmetric
PlumX