Hi, I recently did a little test to try and show the effects of lossy compression codecs such as MP3. I decided to post it here as I know there are a lot of people familiar with the subject and will most likely appreciate the results. 
I had a pair of headphones that developed a fault and one speaker stopped working. The other speaker still worked but seemed to loose some sound resolution. I don't know the technical term for it but I can only guess it lost the ability to replicate certain frequencies. Anyway, I discovered that upon playing compressed audio files I could here the distortion caused by the compression on the audio much more easily than normal. Since some frequences where completely absent, such as heavy bass, the more "less noticed" sounds stand out because they are no longer masked over. These are the sounds the codec is designed to compress more as they're less likely to be noticed upon playback.
For the test I compressed a sample of uncompressed music with 4 popular codecs (MP3, WMA, MP4-AAC and OGG) at 128kbps or 64kbps for each channel. I took the sample from Tazan Boy by Baltimora. I know it's cheesy but it was one of the only few songs that has a segment that shows the effects more clearly. I also did an additional Joint Stereo test for MP3 and along with this I did futher test with MP3, gradually increasing the bitrate to the max of 320kbps. I included the uncompressed sample for comparison. Once the samples were taken I encoded them in FLAC to prevent further compression to make the results fair and to decrease the download size. If you don't have a program that can play these files you can download Winamp, VLC or Media Player Classic which will play these files. For those interested I included the technical details in a TXT file.
The mic I used isn't particularly good and there is some background noise from the computers fans but this doesn't hinder the results that much. Ideally headphones should be used to listen to the samples.
Samples: http://www.usaupload.net/d/8irpxkler87
I had a pair of headphones that developed a fault and one speaker stopped working. The other speaker still worked but seemed to loose some sound resolution. I don't know the technical term for it but I can only guess it lost the ability to replicate certain frequencies. Anyway, I discovered that upon playing compressed audio files I could here the distortion caused by the compression on the audio much more easily than normal. Since some frequences where completely absent, such as heavy bass, the more "less noticed" sounds stand out because they are no longer masked over. These are the sounds the codec is designed to compress more as they're less likely to be noticed upon playback.
For the test I compressed a sample of uncompressed music with 4 popular codecs (MP3, WMA, MP4-AAC and OGG) at 128kbps or 64kbps for each channel. I took the sample from Tazan Boy by Baltimora. I know it's cheesy but it was one of the only few songs that has a segment that shows the effects more clearly. I also did an additional Joint Stereo test for MP3 and along with this I did futher test with MP3, gradually increasing the bitrate to the max of 320kbps. I included the uncompressed sample for comparison. Once the samples were taken I encoded them in FLAC to prevent further compression to make the results fair and to decrease the download size. If you don't have a program that can play these files you can download Winamp, VLC or Media Player Classic which will play these files. For those interested I included the technical details in a TXT file.
The mic I used isn't particularly good and there is some background noise from the computers fans but this doesn't hinder the results that much. Ideally headphones should be used to listen to the samples.
Samples: http://www.usaupload.net/d/8irpxkler87
