Spectrum - Spectral Sound Visualizing Effect - V. 1.0 - Version 1.0 Spectrum is a sound visualization effect based on FFT (Fast Fourier Transform) analysis. This effect is not exactly a scientific implementation but very useful to give visual feedback of the frequency components in playing sound in realtime. It is available for Flash (Player 9, ActionScript 3) and has very good performance. There are numerous parameters for easy configuration and simplified usage with your own Flash projects. You can even define new colors for the gradients.