This is a MATLAB script for computing the auditory contour transform (for details see Lim, Shinn-Cunnigham, and Gardner TJ "Stable time-frequency contours for sprase signal representation"). To get started, download the repository and add the directory to your MATLAB path. Then try running the demo script acontour_demo.m. You should see the following output: 
All parameters are passed as parameter/value pairs (see demo script for an example).
This has been tested with MATLAB R2012b running on Max OS X 10.9. Toolbox requirements: Image Processing Toolbox, Signal Processing Toolbox, Parallel Processing Toolbox.