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by Ernest Cholakis
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In remastering the works on Sondes (Multiple
Soundings) I was primarily concerned with enhancing the clarity while
revealing as much of the sonic detail as possible in each composition. To
accomplish this I created a series of proprietary software processes to be
performed in non-realtime mode. These custom processes are not compromised by
the limitations imposed by realtime mode, and result in superior enhancements
of sound quality. The tasks of each of these processes and their affects on
sound quality and compositional detail are described below.
Equalization is the first signal processing performed. It was performed in
32/64-bit floating point with FIR filters (phase linear filters). Before
optimizing the sound of each recording a very accurate analysis of what the
actual overall spectrum of each track was first required. The strategy of the
equalization was to balance all the frequencies present in the signal so that
all the components would be heard with no dominate frequency band masking or
overpowering any other frequency bands.
The removal of the frequencies below the audible range was also performed
with high-quality digital high-pass filters. This was useful because a common
result of intensive sound editing and mixing of music, especially in the
composition of electroacoustic music, is the creation of sidebands,
particularly in the frequency range between 1 and 20 Hz. The complete removal
of these frequencies added clarity and dynamic range.
Reverberation was also added to the mixed electroacoustic works Continental Rift,
Convergence, and
Liquid Fragments
1, in order to add spaciousness and depth to there overall sound. The
reverberation signals have midrange and treble emphasis (with much less
energy in the bass region). This type of reverberation spectrum was chosen to
enhance the clarity of the transients yet add a spacious component to the
overall sound. The stereo field of the reverberation signals was designed to
minimize the image smearing by having the reverberation signals positioned at
the same point in the stereo field as the source instrument.
A dithering signal was used to convert the 32-bit floating point signal
into the final 16-bit soundfiles for the final CD. A proprietary process of
extracting the 8~12dB below the 16-bit signals noise floor in the original
32-bit floating point soundfile and adding this music into the lowest 8~12dB
region of the final 16-bit signal was also performed.
Finally, the bringing together of these processes in an effective way was
as much a pleasure as a challenge. The repeated listening required for this
remastering gave me the chance to appreciate the rich sonic layers developed
in Randall Smith’s
music. Working with contemporary composers gives me the first hand
opportunity to witness as well as participate in developing technology for
music.
Ernest Cholakis,
Numerical Sound, Toronto
[xi-99]
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