ï~~2- Sonagrams
The sonagrams can be computed by the Mac CPU or by the Sound Accelerator, the second solution
being about 30 times faster with standard computation parameters.
The amplitudes are represented in a linear or log scale on 16 levels addressing one of several
colour tables in the document (the 16 colours can be also grey levels or even black and white).
The features of the DSP sonagram computation algorithm are
- FF1 sizes: from 256 to 16K
- set of standard input windows
- lin or log amplitude scale
- lin or log frequency scale, between 2 variable frequency limits.
The last feature is made possible by a special DSP algorithm that interpolates or averages the
FFT output to the required display format.
3 - Graphical tools
The application provides a complete set of colour graphical draw and editing tools (draw and
paint modes) that are accessible through menus and palettes.
4- Symbol libraries
Graphical symbols can be imported from external library files that may be supplied with the
application or created by the user and containing the most frequently used symbols in a specific
field of application. In draw mode, the user can choose the graphical attributes of a library
symbol to be imported to the document: shape, colour, pattern, etc...The symbol and its
attributes are automatically copied to the clipboard by just clicking on the symbol.
5 - Applications
This software has applications in all the fields where graphical representations are used for
the analysis of existing sounds.The traditional sonagram devices deliver only paper documents
from sounds stored in external media. This software offers, with more features and an improved
quality of the sonagrams, an integrated, low-cost system with an interactive access to sound
and image, graphical editing tools, and the possibility of storing the graphical documents in
files.
In the musical field, the Acousmographe provides several levels of graphical representation
adapted to different needs: automatic sonagram computation for a concert score of diffusion,
symbolic representation for a musical analysis
ICMC 588
