


LXP(1)                   USER COMMANDS                     LXP(1)



NAME
     lxp - extract parameters describing each  excitation  period
     from laryngograph waveform

SYNOPSIS
     lxp (-I) (-T thresh) (-H height) (-A area)  (-R  ratio)  (-S
     sensitivity) (-i item) (-F maxfreq) file

DESCRIPTION
     lxp is a program to extract parameters describing each exci-
     tation period from the laryngograph waveform. It first iden-
     tifies the closure points in an identical manner  to  tx(1),
     then  for  each excitation period as defined by the  closure
     points calculates the following parameters (each  stored  as
     an integer):

     1)         period duration in frames;

     2)         closed  phase  duration  in  frames,  calculating
                point  of  opening  as  most  negative  value  of
                differenced lx in current cycle;

     3)         open phase duration in frames, calculating  point
                of opening likewise.

     4)         closed  phase  duration  in  frames,  calculating
                point  of  opening as that which divides lx range
                in current excitation period such  that  (max  lx
                value - opening lx value):(opening lx value - min
                lx value) is ratio given by -R parameter;

     5)         open phase duration in frames, calculating  point
                of opening likewise;

     6)         height of peak of differenced lx waveform at clo-
                sure (arbitrary units);

     7)         amplitude  of  lx  waveform,  i.e.  lx  range  in
                current excitation period (normalised by dividing
                by average amplitude over sample, and  multiplied
                by 100000 for storage as an integer);

     8)         width, in  frames,  of  peak  of  differenced  lx
                waveform at closure.

     Options and their meanings are:

     -I         Identify program and exit.

     -Tthresh   Threshold  factor  for  peak  detection  (default
                1.0).




SPAR                    Last change: UCL                        1






LXP(1)                   USER COMMANDS                     LXP(1)



     -Hheight   Height  factor  for  peak  significance  (default
                4.0).

     -Aarea     Area factor for peak significance (default 6.0).

     -Ssensitivity
                Sensitivity of peak  detection:  the  larger  the
                value,  the more peaks are likely to be detected.
                Users are advised that -S is easier to  use  than
                -T, -H or -A. Default 1.0.

     -Rratio    Ratio in which opening point divides range of  Lx
                in current cycle (default 2.333, i.e. 7:3).

     -Fmaxfreq  Specify maximum frequency, in Hz,  to  be  recog-
                nised by program; default 800Hz.

     -iitem     Select input item type & subtype.

INPUT ITEMS
     2.xx       Any excitation waveform item

OUTPUT ITEMS
     3          Tx and other Lx parameters

VERSION/AUTHOR
     3.0 - Peter Davies.  Includes  amendment  to  correct  "zero
     closed phase" .

     3.1 - adds sensitivity & max freq options.

     3.2 - adds sfs file handling.

BUGS
SOURCE
     /users/mark/sfs/man/../ucl-priv/lxp.c



















SPAR                    Last change: UCL                        2



