Lossless Audio Checker - A utility to check whether an audio file is truly lossless or not.
Friture - Friture is a program designed to analyze audio input in real-time.
Spek - Spek helps to analyse your audio files by showing their spectrogram.
xoscope - Xoscope uses the input of your Sound Card, EsounD and/or a ProbeScope/osziFOX and Bitscope-Hardware.
REW - REW is free room acoustics analysis software for measuring and analysing room and loudspeaker...
Signalizer - Signalizer is an all-in-one signal visualizing package for VST, VST3 and AudioUnits