FFT Spectra

FFT Spectra is a software tool that enables users to visualize frequency spectra of audio signals. The software is useful for a variety of purposes, such as determining if a person is singing or whistling in tune or tuning a guitar. One unique aspect of the software is its ability to model the sound of a didgeridoo, which was the inspiration for developing the software.

The physics theory behind the didgeridoo explains that when air is blown into a cylindrical tube and the lips are vibrated, standing waves develop inside the tube. The software displays a graph indicating a position along the tube on the horizontal axis and the amount of pressure variation from atmospheric pressure on the vertical axis. The graph shows a node at the end of the tube, where the air leaves, and an antinode at the point where the air is blown in.

This node/antinode structure allows only specific frequencies to be developed as standing waves, while other frequencies are not possible. The software displays a red curve indicating the minimal frequency present in the sound of the didgeridoo. The user can adjust the curve using the software's controls to see how changes in frequency affect the sound waves, including the disappearance or appearance of peaks at specific frequencies.

The software has a few requirements, such as version 2.2.x of GTK+, but otherwise is easy to use and intuitive. The latest release includes a new display mode for waves, as well as many minor improvements and bugfixes. Overall, FFT Spectra provides a helpful tool for musicians and anyone interested in understanding the physics of sound waves.