comparison man/man1/gencgm.1 @ 0:5242703e91d3 tip

Initial checkin for AIM92 aimR8.2 (last updated May 1997).

+.TH GENCGM 1 "11 May 1995" 
+.LP 
+.SH NAME 
+.LP 
+gencgm \- generate a cochleogram 
+.LP 
+.SH SYNOPSIS 
+.LP 
+gencgm [ option=value | -option ] [ filename ] 
+.LP 
+.SH DESCRIPTION 
+.LP
+
+Gencgm converts the input wave into a simulated neural activity
+pattern (NAP) and summarises the NAP as a sequence of excitation
+patterns (EPNs) that collectively form a 'cochleogram' (CGM). The
+operation takes place in three stages: spectral analysis, neural
+encoding, and temporal integration. In the spectral analysis stage,
+the input wave is converted into an array of filtered waves, one for
+each channel of a gammatone auditory filterbank. The surface of the
+array of filtered waves is AIM's representation of basilar membrane
+motion (BMM) as a function of time (manaim genbmm). In the neural
+encoding stage, compression, adaptation and suppression, are used to
+convert each wave from the filterbank into a simulation of the
+aggregate neural response to that wave. The array of responses is
+AIM's simulation of the neural activity pattern (NAP) in the auditory
+nerve at about the level of the cochlear nucleus (manaim gennap).
+Finally, the NAP is converted into a sequence of excitation patterns
+(EPNs) by calculating the envelope of the NAP and extracting spectral
+slices from the envelope every 'frstep_epn' ms. The envelope is
+calculated continuously, by lowpass filtering the individual channels
+of the NAP as they flow from the cochlea simulation.  
+.LP
+When the sequence of excitation patterns is presented in spectrogram
+format, it is referred to as a 'cochleogram' (CGM). The spectrogram
+format has time on the abscissa (x-axis), filter centre-frequency on
+the ordinate (y-axis), and activity level as the degree of black in
+the display.  In AIM, the suffix 'cgm' is used to distinguish this
+spectral representation from the other spectral representations
+provided by the software ('asa' auditory spectral analysis, 'sgm'
+auditory spectrogram, and 'epn' excitation pattern).
+.LP 
+The NAP generated by gencgm is the same as that produced by gennap
+(manaim gennap).  The primary differences are in the display defaults
+and the inclusion of the Leaky Integration used to construct the
+excitation patterns that form the cochleogram.  As a result, this
+manual entry is restricted to describing the option values that differ
+from those in gennap and the additional options required to control
+the Leaky Integration.
+.LP
+.SH DISPLAY DEFAULTS
+.LP
+The default values for three of the display options are reset to
+produce a spectrographic format rather than a landscape. Specifically,
+display=greyscale, bottom=0 and top=2500. The number of channels is
+set to 128 for compatibility with the auditory spectrum modules,
+genasa and genepn.  When using AIM as a preprocessor for speech
+recognition the number of channels would typically be reduced to
+between 24 and 32.  Use option 'downsample' if it is necessary to
+reduce the output to less than 24 channels across the speech range.
+.LP
+.SH COMPRESSION AND LEAKY INTEGRATION
+.LP
+Compression and lowpass filtering are activated after the neural
+encoding stage:
+.LP
+.SS "Compression"
+.PP
+Cochleograms are usually produced via the functional route in AIM. In
+this case, compress is set on
+.LP
+.TP 13
+compress
+Logarithmic compressor switch
+.RS
+Switch. Default: on.
+.RE
+.RS
+.LP
+Note: The compressor in the functional route of AIM is logarithmic and
+it screens out negative BMM values before compression. This rectifies
+the wave during the compression process and so the separate rectify
+option is left off. 
+.RE
+.LP
+.RS
+.LP
+Note: The compressor in the physiological route of AIM is an integral
+part of the tlf module, so when using this route to produce a
+cochleogram, turn off the logarithmic compressor
+(i.e. compress=off). The compressor in tlf does not screen out
+negative values so it is also important to set rectify=on.
+.RE
+.RS
+.LP
+Full wave rectification is produced if rectify is set to 2. This will
+lead to a smoother cochleogram from both the physiological and the
+functional versions of AIM.
+.RE
+.LP
+.SS "Transduction"
+.PP
+.LP
+.TP 13
+transduction
+Neural transduction switch (at, meddis, off)
+.RS
+Switch. Default: at.
+
+.RE
+.LP
+.SS "Leaky Integration"
+.PP
+.LP
+.TP 13
+stages_idt
+Number of stages of lowpass filtering
+.RS
+Default unit: scalar. Default value: 2
+.RE
+.TP 13
+tup_idt
+The time constant for each filter stage
+.RS
+Default unit: ms. Default value: 8 ms.
+.RE
+.LP 
+The Equivalent Rectandular Duration (ERD) of a two stage lowpass
+filter is about 1.6 times the time constant of each stage, or
+12.8 ms in the current case.
+.TP 13
+frstep_epn
+The time between successive spectral frames
+.RS
+Default unit: ms. Default value: 10 ms.
+.RE
+.LP
+With a frstep_epn of 10 ms, gencgm will produce spectral frames at a
+rate of 100 per second.
+.LP
+.TP 13
+downsample
+The time between successive spectral frames. 
+.RS
+Default unit: ms. Default value: 10 ms.
+.RE
+.LP
+Downsample is simply another name for frstep_epn, provided to
+facilitate a different mode of thinking about time-series data.
+.LP
+.SH FILES
+.LP
+.TP 13
+.gencgmrc 
+The options file for gencgm.
+.LP
+.SH SEE ALSO
+.LP
+gensgm, genasa, genepn, gennap, genbmm
+.LP
+.SH BUGS
+.LP
+None currently known.
+.SH COPYRIGHT
+.LP
+Copyright (c) Applied Psychology Unit, Medical Research Council, 1995
+.LP
+Permission to use, copy, modify, and distribute this software without fee 
+is hereby granted for research purposes, provided that this copyright 
+notice appears in all copies and in all supporting documentation, and that 
+the software is not redistributed for any fee (except for a nominal 
+shipping charge). Anyone wanting to incorporate all or part of this 
+software in a commercial product must obtain a license from the Medical 
+Research Council.
+.LP
+The MRC makes no representations about the suitability of this 
+software for any purpose.  It is provided "as is" without express or 
+implied warranty.
+.LP
+THE MRC DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING 
+ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL 
+THE A.P.U. BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES 
+OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, 
+WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, 
+ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS 
+SOFTWARE.
+.LP
+.SH ACKNOWLEDGEMENTS
+.LP
+The AIM software was developed for Unix workstations by John
+Holdsworth and Mike Allerhand of the MRC APU, under the direction of
+Roy Patterson. The physiological version of AIM was developed by
+Christian Giguere. The options handler is by Paul Manson. The revised
+SAI module is by Jay Datta. Michael Akeroyd extended the postscript
+facilites and developed the xreview routine for auditory image
+cartoons.
+.LP
+The project was supported by the MRC and grants from the U.K. Defense
+Research Agency, Farnborough (Research Contract 2239); the EEC Esprit
+BR Porgramme, Project ACTS (3207); and the U.K. Hearing Research Trust.
+