Audacity is a professional audio editing software with extensive and advanced music editing features. It supports importing and exporting to many audio formats. Once files are imported editing becomes easy with many useful tools such as zooming, multitrack editing, copy-pasting desired segments etc. The program uses Fourier algorithm for audio spectrum analysis and can remove background noise. Very importantly, you can adjust music tempo without distorting its pitch. You can make voice overs, covnert cassette to digital files and edit your music files using a vast array of useful tools.