Programming Note No. 3 Ravi Kochhar Dept. Neurophysiology UW-Madison Aug. 10, 1989 Rev. level : 1.001 (7/12/96)
The programs described below are collectively referred to as the "PIN Programs", and are used for collecting and analyzing data for the physical acoustic measurements in Room 18. The experimental protocol and analysis procedures are the work of A.Musicant, J.Chan and J.E.Hind, and they should be consulted for more details.
This note is an attempt to list the available programs in one place. No other formal documentation exists at this time. The description below is for programs on the VAX only.
The available programs are :
PIN Data collection and some analysis WORLD Contour plots mapped to world projection CONT3D 3-D surface contour plots CONTUR Contour plots mapped to rectangular projection POLAR Polar intensity level plots GRAD Gradient computation across contours APOLAR Polar arrival time plots ATIME Arrival time plotting/computation STATPK General purpose plotting/data manipulation
It is expected that eventually the functions of all these programs will be merged into PIN and/or STATPK.
This program is used for both data collection and analysis. It is started by typing PIN at any terminal, and presents the user with a menu of available options. If option 7 is selected, then PIN branches to the data collection section, and the user is presented with a number of queries relating to data collection.
Note that it is possible to automate the data collection to an extent by first setting up the data collection paradigm as commands in a "macro" file. In that case, data collection, once started, can proceed un-attended according to the commands in the macro file.
At present, data collection consists mainly of moving the speaker along an imaginary sphere via a mechanical arm (designed by Musicant, Chan and Hind), presenting a series of repetitive stimuli (clicks or tone pips), and averaging the analog signal at microphones positioned at the subject's left and/or right ear. Data storage is in a standard data file created using the program SETUP.
The program PIN also performs certain analysis functions. If option 8 (data analysis) is selected, the user is presented with analysis options. At present, the analyses performed by PIN are of three separate types, as follows :
(a) Freq Domain : This consists of computing the spectrum (using an FFT) of one or more of the recorded time domain waveforms from the raw data file and transferring the results to a STATPK file. Amplitude and/or Phase values can be transferred for the left and/or right ears. Further analysis is then done using STATPK or other programs.
(b) Time Domain - Arrival Time : This analysis consists of estimating the arrival time of the waveform at each position of the speaker in space and building up a two dimensional matrix of arrival times with the columns being the azimuths and the rows being the elevations. This is done for each ear and a third matrix is then computed by subtracting the arrival times at the right ear from those at the left ear (i.e. an interaural delay). These three matrices are stored back as three separate data sets in a STATPK file.
(c) Time Domain - Zero Crossing : This analysis is most suitable for data collected using tone pips rather than clicks. It attempts to examine variations in the interval between successive zero crossings as a function of time. This option can be using for initial graphics displays and can also be used in a more automated mode to transfer results to a STATPK file.
This program plots iso-intensity, iso-arrival-time, or iso-delay curves on a hemisphere using a Lambert Azimuthal Equal Area projection (ref. no. 1). The contouring itself is done using the Precision Visuals Inc. contouring package (ref. no. 2). The program uses a STATPK format file as input.
This program plots amplitude or time (delay) as a function of azimuth or elevation and frequency. The plot is a pseudo 3-dimensional surface contour plot where (typically) the X-axis is frequency, the Y-axis is either elevation or azimuth, and the Z-axis is intensity or interaural delay. Data input is from a STATPK data file.
This program plots iso-intensity or iso-delay contours on a rectangular projection where azimuth varies along the X-direction and elevation varies along Y. Data input is from a STATPK data set.
This program plots intensity (amplitude) as a function of either azimuth or elevation as a "polar" plot where amplitude varies along the radial direction and azimuth/elevation along the theta direction. Data input is from a STATPK file.
This program computes the "gradient" (i.e. the slope) along iso-intensity or iso-delay contours generated as a function of elevation and azimuth. The gradients are computed in the iso-elevation and iso-azimuth directions and stored as new data sets in a STATPK file. Data input is from a STATPK data set.
This program is very similar to "POLAR" described above except that this one is optimized for display of time rather than intensity.
This program is used for checking various ways of defining an "arrival" time for the time domain signal. It is used mostly for initial exploration of the data. It graphs both the left and right ear waveforms on one plot and marks the arrival times with vertical bars. Data input is from a STATPK data file.
This program is used for general purpose data manipulation and initial exploration. More details on STATPK are in Ref. no. 3.
(1) "Map Projections - A Working Manual", J.P.Snyder, U.S.Geological Survey Professional Paper # 1395, U.S. Govt. printing office, Washington, 1987, pp 182-190.
(2) "Contouring System Users Guide", Precision Visuals, 1985.
(3) "STATPK - Users Guide", R.Kochhar, Tech. Report # 9, Dept. of Neurophysiology, in preparation.
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