As a result of such studies, the Wigner Distribution (WD),
originally developed for joint distribution in Quantum Mechanics, has been
applied to signal analysis and its superiority has been established for
accurate time-frequency representation. In the context of the representation
of musical timbres, the WD allows accurate analysis of both temporal and spectral
details, and thereby facilitates synthetic processing of both
transient and steady-state aspects of musical tones. This in turn opens up previously
unexplored vistas in timbre space in that timbre manipulation is not confined to
spectral processing. With an ability to see the full detail of temporal and spectral
composition of musical timbres comes the desire to manipulate these same details for the purpose
of creative, musical expression.
One approach to the exploration of timbre space is based on the possibilities
inherent in morphing between two choosen timbres.The concept of visual
morphing is familiar to many from special effects processing in cinema. A good example
is where we are shown a young face gradually and smoothly age as it moves from youth to old age.
This is achieved by using two frames - one young and the other old - and manipulating various
perceptually significant parameters so that the presented face appears to move from
the youthful starting frame to the aged finishing frame. An exactly
analogous process may be applied to musical timbres. For example, we may choose a violin
starting timbre and a flute finishing timbre and manipulate various
important (spectral and temporal) features so that we can move smoothly between them. By so doing
we open up new parts of timbre space which nevertheless are not entirely unknown to us in that we
would at least be opperating between the known boundaries of 'violin' and 'flute', or whatever
other timbres we had choosen at the outset.
Thus Morphing would provide the composer with access to a much richer timbre palette
than here before, in that previously inexplored regions of timbre space could be made
available for creative manipulation. By basing such morphing tools on WDs of musical tones, rather
than Spectrograms, representational distortions would be minimized and detailed
spectral and temporal features of real instrument tones would be made much clearer for the purposes
of computational analysis and synthesis.
With regard to research, it is proposed to develop a computer-based tool which would facilitate
timbre morphing and provide the composer with a vastly expanded timbre palette. The work would
involve a number of stages:
As with the case of the development of many application tools, the cross-disciplinary nature of the
proposed research requires a significant input from both the technological and the musical domains.
To be truely useful as a tool for composition, it is essential that the researcher be well versed in
musical composition and have appreciation of those features which would be important from the
perspective of the musician. Obviously the reverse scenario also holds true in that the development
of the type of tools which might be desired by the composer for timbre exploration requires
considerable technical expertise. It is believed, therefore that this project is an ideal vehicle for
interaction between the DIT College of Music and TCD Department of Electronic
and Electrical Engineering, as both parties have a strong interest in aspects of the other's
domain of activity. Research in audio and musical acoustics has been ongoing in TCD Department of
Electronic and Electrical Engineering for over a decade, while DIT College of Music have an emerging
interest in the exploration of technological aids for composition and performance. Given such, it is
hoped that significant advantages will accrue to both parties through the involvment and interaction
which the proposed project will necessitate.