use this, my school teachers taught us, very useful~ :
Audacity:
http://audacity.sourceforge.net/download/windows
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1. Create a new project :
This is very important!
Audacity writes all the changed and recorded audio to a directory called Projectname_data, which is located right where you saved the project file itself.
Thus, select and choose a location and filename for your project.
Please note that when you startup Audacity fresh, only the " Save As..." menu option is available.
To save your project later on, you can also use the keyboard shortcut : CTRL+S
2. Check the Preferences :
Again, this is very important!
Press CTRL+P or go to ...
...then check if the right output is selected :
...set the sample rate of your choice... (44.1 kHz is the default)
...and here's a crucial screen :
The File Formats settings need discussing at this point.
When importing uncompressed audio, there are two ways to do it. "Make a copy of the original before editing" means, that Audacity actually copies the entire audio file that you imported in to its project data directory and in the process sets up the little overview graphics, whose descriptions get stored in the project data directory too.
The second way is to use the original imported audio. You may think we're actually editing this file, but no we aren't. In fact, Audacity will now read the imported file once and simply create the graphics overviews for them in the data directory, and subsequently write to disk all the audio data that you change. The original file is only used for playback. All audio that remains unchanged will be played from the original file.
The advantage of choosing to make a copy of the original is that you avoid trouble, should anything in the original file change.
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*** For more, you can go to that website to know more how to use, have chinese also.