Internet Archaeol. 16. Mlekuz. Example

The model in action

The main purpose here is to describe how to obtain, install and engage with the soundscape model described in the paper.

Downloading and installation

It assumed that the user is running a Unix Operating System (Linux, FreeBSD, Mac OS X; although this software can also run under Windows) and has successfully installed the GRASS GIS package. GRASS (Geographic Resources Analysis System) is an open source, free software geographical system, which operates on various computer platforms and is released under GNU General Public License.

The model source code can be downloaded from here. The package includes the source code of the modules (shell and Perl scripts) and detailed help and installation documentation. The software is in a constant state of development. If you are interested in this work, would like to contribute or need help, please contact me. The package is released under GNU General Public License.

Download the package to your home directory and unpack it with tar xvfz soundscape.tar.gz. This will create a directory named soundscape, containing the relevant files.

Sample session

This sample session assumes that you are using the sample mapset, prepared for use with GRASS, which can be downloaded from here. It also requires some familiarity with GRASS.

Download the sample mapset to your home directory and unpack it with tar xvfz sndsample.tar.gz. This will create a GRASS database directory named sndsample. Note that the user input is displayed in fixed-width font while the GRASS database names are shown in bold.

Start GRASS with the grass5 command, and enter information on the GRASS startup screen. The GRASS location is sndsample, the mapset is PERMANENT and the database is your home directory. Change the directory to the soundscape using cd soundscape. The GRASS command line prompt should now be 'GRASS:~/soundscape >'.

Now you are ready to explore the soundscape models. In this session, we will create binary and fuzzy acoustic horizons from a church bell located at coordinate 50, 50 (middle of the map) with sound intensity of 90 dB[A] and frequency of 750Hz (equals wavelength of 0.44m; frequency is calculated by dividing the speed of sound [330m/s] with its wavelength).

First we create a map of three-dimensional distances (called dist) from the church bell. The map dem is a digital elevation model, provided in the sample mapset; 50, 50 and 370 are the three-dimensional coordinates (easting, northing and height) of the church bell (height can be determined using the d.what.rast module which is a part of the GRASS package).

GRASS:~/soundcape >./d3d.sh dem dist 50 50 370

Then we create a map of 'sound shadows' called shadow using the raytracing algorithm.

GRASS:~/soundscape >./raytrace.sh dist shadow 50 50

Now we are going to create a binary acoustic horizon, binary, from the church bell. The numeric argument 0.44 is the wavelength of the sound in metres while 90 is the sound intensity in decibels.

GRASS:~/soundscape >./binary_horizon.sh 0.44 90 dist shadow binary

Finally, a fuzzy acoustic horizon called fuzzy is created with the same arguments as the binary horizon.

GRASS:~/soundscape >./fuzzy_horizon.pl 0.44 90 dist shadow binary

Now you can start exploring the beautiful world of past soundscapes!