Thanks WinOScentral for this rather nice pointer to an interesting article over at PC World concering audio formats and the codecs used to store our music on our computers..
Many people complain that compressed audio doesn"t sound as good as CD audio. To verify that claim, we subjected a group of typical listeners to blind tests to see whether they could tell the difference between music from CDs and compressed versions of the songs in a variety of file formats. We also asked the testers to rate the compressed versions on a quality scale.
From each of five pieces of music, we ripped a 30-second clip from a CD to a .wav file. The five music selections were an acoustic version of Daughter by Pearl Jam, Radioactivity by Kraftwerk, a cellos-only version of Wherever I May Roam by Apocalyptica, a live version of Time by Pink Floyd, and O Fortuna from Carl Orff"s Carmina Burana.
We compressed each clip to a variety of bit rates using Windows Media Encoder for the WMA format, Real Jukebox Plus for the RealAudio format, MusicMatch Jukebox Plus for the MP3 format, and RealJukebox Plus with the Dolby AAC plug-in for Dolby"s AAC format.
We then played back both the original files and the uncompressed versions to 30 testers (mainly PC World staff, but we also got representatives from Dolby laboratories, Microsoft, and Real Networks to participate). We asked them to identify the compressed versions. We used a double-blind testing methodology in which each tester was given three files to listen to, called A, B, and C: The A file was the .Wav file ripped directly from the CD. The other two were either the .Wav file or a compressed version.