Audacity is a free cross-platform audio recording and editing software. You can download the latest version from http://audacity.sourceforge.net/. Although Version 2.06 says it is for Mac OS X 10.4 to 10.9.x, it will also work for Yosemite.
Download the DMG file, double-click on it, and drag the Audacity folder into your Applications directory. From the launch pad, click on the Audacity application to open it.
You can click on the Quick Help, Manual, Wiki, and Forum links to understand more about the software and its features. Click on OK to continue.
I am not a sound engineer, so I am really not the right person to tell you or explain what each of the headings does. All I can really say is that if you know a thing or two about sound programming or engineering, you can really do magic with this free and open source application. For example, we can reduce the size of a file by lowering the frequency of a file from 44 kHz to 22 kHz, as shown in the following...