Sonic Visualizer is a powerful analysis tool for audio files. It is both cross-platform and open-source application being developed by some of the very smart folks at the University in London, UK. The purpose of this tool is not to just be able to manipulate or edit the audio files, but also to analyze them and study the musical recordings. This tool could be of interest to the musicians, recording artists, archivists, signal processing researchers etc.
At first, it looks very similar to another open-source project called Audacity, but you will see the differences as you start using it. There is a time speed slider control using which you can speed up or slow down the playback. This is very useful if you are analyzing a particular section of the audio files. Another interesting feature is the ability to loop any section of the audio file which might help you get the details of the track in that portion of the playback.
If these and many more features are not enough for you, then you can make Sonic Visualizer even more powerful by using the various plugins. These plugins called Vamp plugins are available for various platforms and can be downloaded free of charge from the Vamp plugins website. They can be used for automatic analysis of key, temp, beats, harmonics etc.
Apart from these, Sonic Visualizer is fully compatible with the LADSPA plugins designed to work with Audacity. So you can download the Audacity plugins from their website and use them in Sonic Visualizer for adding some cool effects to your audio playback.
During the analysis of audio files, you can annotate them by adding text labels defining time points, segments and curves in the audio waveform. These notes are not saved inside the audio files, but they are rather saved in a separate SV file that can be edited or deleted any time.
Conclusion: Sonic Visualizer is a powerful audio analysis tool for people interested in the details of the audio research. It supports various plugins and can be used in both Linux and Windows.
You can download Sonic Visualizer from http://www.sonicvisualiser.org/.