3D Spatialization of Sound is a software that brings the 3D spatializer library from CRC to Linux/X11 platform for enhancing sound quality and experience with spatialized audio.
To build the X11 implementation, follow these three steps: 1) make, 2) cp audio-filter /usr/local/bin, and 3) mpg123 -m -s some_music.mp3 | audio-filter | aplay -S -s 44100 -f s16l -. The audio-filter is implemented as a filter and reads signed 16 bit mono input at 44100 khz from stdin, outputting signed 16 bit stereo, 44100 khz output to stdout. The mpg123 can be replaced with any sound source generating a signed 16 bit 44100 khz mono signal. The sound player, "aplay", which comes with ALSA Linux sound driver, can also be substituted with "play" from the sox package or "ampctl" or any other sound player that reads 44100 khz, signed 16 bit stereo raw data from stdin. To use the "sox" play script, replace the "aplay" command line with "play -c 2 -f s -r 44100 -s w -t raw -".
On startup, a 640x480 window will come up displaying some cryptic writing on the top, a filled circle with an arrow pointing right, and an empty circle slightly to the right of the circle with arrow. A thing to note is that just like the original Windows implementation, the axis's are reversed. The arrow on the "head" is pointing "forward". Therefore, in the default startup configuration, the sound is located in front of the listener. Moving the sound source "up" moves it to the left of the listener, and "down" to the right. You can visualize this by turning your monitor 90 degrees counterclockwise. The filled circle with an arrow represents the "head," and the empty circle symbolizes the "sound source."
To move the "sound source" around, click on any position in the window, or click on the "sound source" circle and drag it to the preferred position. The soundfield dynamically updates as you do this. You can move the "head" by navigating the mouse to the desired position and right-clicking. The "head" icon will move to the new location, and the soundfield will update accordingly. Overall, the 3D Spatialization of Sound is a fascinating and valuable software tool for those in the audio engineering and production field to experiment with.