Audacity 2.1

Audicity is a feature-rich audio recording and editing tool. This program can be used to record audio from your PC, the Internet, radio and so on.
Once you import the file, you'll see the track displayed in the waveform. This graph gives you basic information about the sound parameters, such as the pitch, rate and loudness; although by default those are not as detailed as professional speech analyzers are offering.

On the top of the screen you can get the basic functions (Play, Record, Stop, Pause, Skip to start/end) and the basic tool palette that would help make editing easier and experiment with your own tracks.
The most important tool to start editing is the Selection Tool which highlights a particular area, so that you could play it separately and edit.

In addition to the most important functions like Cut, Copy, Paste, Delete, and track splitting features, Audicity offers a long list of useful effects which includes Repair, Change speed/tempo, Echo, Noise reduction, Fading, Cross fading and many other.

You can combine several tracks using Time Shift Tool changing the position of tracks relative to one another in time. This function is the most useful for those who are composing and need to combine lead and back vocal.
This tool can also convert audio files to WAV, AIFF, AU, FLAC formats.

It could be a bit difficult to work with this program for those who have never dealt with such utilities before. However, with a little time and a little practice you are sure to master it. To sum it up, Audicity is very helpful for audio files live recording and editing.