Aglaophone is a system of interconnectable modules for the recording, processing, and playback of real-time audio. It features a real-time spectrogram display for visualization along with a number of processing modules. Modules include filters, downsamplers, upsamplers, and quantizers. An MP3 comparison module allows interactive blind comparison of MP3 encoded audio with CD audio, demonstrations of spectral imaging, quantization, and Smith-Barnwell filter bank based wavelet decomposition are included, and there is a module that can perform an automatic spectral analysis of a speaker system.
Baudline is a time-frequency browser designed for scientific visualization of the spectral domain. Signal analysis is performed by Fourier, correlation, and raster transforms that create colorful spectrograms with vibrant detail. Conduct test and measurement experiments with the built in function generator, or play back audio files with a multitude of effects and filters. The baudline signal analyzer combines fast digital signal processing, versatile high speed displays, and continuous capture tools for hunting down and studying elusive signal characteristics.
eXtace is a visual sound display/analysis program. It requires Esound (esd) for its audio source. It includes various fast fourier transforms of the audio data in realtime. Its displays include a 3D wireframe flying landscape, a 3D textured flying landscape, a 16-256 channel graphic EQ, three types of scopes, a 3D "spike" flying landscape, and two forms of spectragrams. The 3D traces can be picked up, manipulated, and displayed at nearly any angle. eXtace also features a 3D direction control widget for controlling the angle and speed at which the trace runs away and a gradient/colormap editor for changing the colormap to suit your needs. No OpenGL is required.
HASAS (HydroAcoustic Signal Analysis System) is a modular system for passive sonar signal analysis. It can be used for biological research or surveillance, for example. The soundcard is used as input device, and it currently includes all the very basic functionality; beamformed audio, direction finding, level histogram, LOFAR/DEMON (narrowband spectrogram), wideband spectrogram, and raw audio.
MPEG Maaate (MPEG audio analysis toolkit) is a C++ toolkit to parse and analyse audio data in the frequency domain, e.g. analysing MPEG-1/2 Layers 1-3 audio files in the compressed domain. It makes the encoded fields of an MPEG audio stream accessible and provides some content analysis functions like silence detection.