Spectro - Spectro is a freeware audio file analyzer for windows.
Visual Analyser - A powerful software implementing a Spectrum Analyzer, Oscilloscope, Frequency meter, Distorsiometer, Volt meter and more... plus complete D/A conversion, ZRLC, Impedance meter
Friture - Friture is a program designed to analyze audio input in real-time.
xoscope - Xoscope uses the input of your Sound Card, EsounD and/or a ProbeScope/osziFOX and Bitscope-Hardware.
Lossless Audio Checker - A utility to check whether an audio file is truly lossless or not.
Signalizer - Signalizer is an all-in-one signal visualizing package for VST, VST3 and AudioUnits