FFTExplorer is a GUI that performs spectral analysis on real-time data from a sound card or other source, and can analyze the spectra of various sound file types. It can display time-domain and frequency-domain data in a number of ways, and is an easy-to-use introduction to the topic of spectrum analysis. Beyond performing a fast Fourier transform on arbitrary data sources, it can also perform moving average noise reduction for the treatment of signals accompanied by noise. It contains a lengthy combination essay/help file on the various topics the program covers, some step-by-step examples using its own internal signal source, and a detailed example using an external source. (Source: http://freecode.com/)