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

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

+.TH GENSGM 1 "11 May 1995" 
+.LP 
+.SH NAME 
+.LP 
+gensgm \- generate auditory spectrogram 
+.LP 
+.SH SYNOPSIS 
+.LP 
+gensgm [ option=value | -option ] [ filename ] 
+.LP 
+.SH DESCRIPTION 
+.LP 
+The gensgm module of the AIM software performs a time-domain spectral
+analysis using a bank of auditory filters, and summarises the
+information in an auditory spectrogram, that is, a spectrogram with
+auditory frequency resolution and temporal resolution, rather than the
+fixed frequency and temporal resolution of traditional speech
+preprocessors.  The spectral analysis converts the input wave 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. The auditory spectrogram is a plot of a sequence of spectral
+slices extracted from the envelope of the BMM every 'frstep_epn'
+ms. The envelope is calculated continuously, by rectifing,
+compressing, and lowpass filtering the individual BMM waves as they
+flow from the filterbank.
+.LP
+The frequency resolution of the analysis varies with the center
+frequency of the channel as in the auditory system, and the
+distribution of channels across frequency is chosen to match that in
+the auditory system (Patterson and Moore, 1986).  Thus, the auditory
+spectrogram is a greyscale plot of the activity in each channel
+(shades of black) as a function of time (the abscissa) and the centre
+frequency of the auditory filter (the ordinate) in ERB's.  The
+representation is referred to as an auditory spectrogram (SGM) to
+distinguish it from more traditional spectrograms based on Fourier,
+LPC or cepstral analysis. In AIM, the suffix 'sgm' is used to
+distinguish this spectral representation from the other spectral
+representations provided by the software ('asa' auditory spectral
+analysis, 'cgm' cochleogram, and 'epn' excitation pattern).
+.LP
+The spectral analysis performed by gensgm is the same as that
+performed by genbmm (manaim genbmm). The primary differences are in
+the display defaults and the inclusion of the Compression and Leaky
+Integration modules used to produce the spectral slices that form the
+spectrogram. As a result, this manual entry is restricted to
+describing the option values that differ from those in genbmm and the
+additional options required to control the Compression and 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 and the neural
+encoding stage that comes between them is turned off:
+.LP
+.SS "Compression"
+.PP
+Auditory spectra 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 auditory
+spectra, 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
+option value leads to smoother spectrograms. It is also useful when
+calculating envelopes with genasa.
+.RE
+.LP
+.SS "Transduction"
+.PP
+.LP
+.TP 13
+transduction
+Neural transduction switch (at, meddis, off)
+.RS
+Switch. Default: off.
+.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, gensgm 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
+ .gensgmrc 
+The options file for gensgm.
+.LP
+.SH SEE ALSO
+.LP
+genasa, genbmm, genepn, gencgm
+.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.
+