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.
Spectralissime - Spectralissime High Definition Spectrum Analyzer by V.Burel
sndpeek - a real-time audio visualization tool (animated, 3D)
TrueRTA - Audio analyzer application for testing and evaluating audio systems using a Windows PC with basic...
Spectro - Spectro is a freeware audio file analyzer for windows.