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.
DansTuner is a program to tell you if you are playing a pitch in tune. Major features include automatic discovery of which note you are trying to play (good for trumpet, singer, etc.), the ability to play a guide tone at a configurable volume, a graphical moving "needle" with a red/green display and detail about how flat or sharp you are, and an easily configurable background noise threshold.
jMax is a visual programming environment for building interactive real-time musical and multimedia applications by allowing the user to interactively design dataflow circuits. The basic data types that can go through are integers, symbols, lists, etc. It is an event-driven system and has been used for MIDI processing. A second part of the system (DSP) allows a continuous signal to flow through a circuit, which is most useful for PCM sound (ie. microphone, sound files, etc.). The system is extensible by using shared libraries, you may add data processor types, data types, GUI elements, device types, and more. Data processors may also be designed as circuits and reused.
Nyquist is an elegant and powerful language for sound synthesis and music composition. Unlike score languages that tend to deal only with events, or signal processing languages that tend to deal only with signals and synthesis, it handles both in a single integrated system. It is also flexible and easy to use because it is based on an interactive Lisp interpreter. You can design instruments by combining functions (much as you would using the orchestra languages of Music V, cmusic, or Csound). You can call upon these instruments and generate a sound just by typing a simple expression. You can combine simple expressions into complex ones to create a whole composition. It runs under any Unix environment, MacOS, Windows 95, and Windows NT, and it produces sound files as output (or direct audio output under Windows).