Mixere 

Mixere is a free Windows application for mixing audio files. Its simple, spreadsheet-like interface is ideal for live performance, and especially sound collage. Dynamic looping, fully automated sliders, gradual mute/solo operations, and more.
multitrack audio mixer sound collage

DSSF3 Basic 

The free version of the advanced sound measurement software DSSF3 is now available. It consists of the signal generator, sound recorder and player, and the peak level meter.
sound noise measurement oscilloscope realtime acf spl iacc iacf spectrum fft audio signal generator