I have prepared three digital audio files of a short musical loop containing both instruments and voices. The files were recorded at the same sampling rates and resolutions but were compressed using different codecs and bit rates.
The first two examples allow you to compare the QDesign and MP3 codecs using the same quality setting of 48 kilobits per second (kbps) bit rate. The final example demonstrates a higher quality recording that is possible by compressing at the higher 128 kbps bit rate. In all cases, however, the file size is impressively small. The uncompressed audio for this stereo excerpt would consume 2.6 megabytes (2600 kilobytes) and would take much longer to download.
Judgments about compression quality are subjective. To my ear, the third example is far superior because the hi-hat is more brilliant and the range of audible frequencies is greater. In general, with MP3 compression you can expect good results when compressing at 128 kbps bit rate and you can expect the file size to be about 1/10th of that of the original uncompressed audio file.
All excerpts were recorded in stereo at 44 kHz sampling rate, 16-bit sampling resolution. File sizes are marked in bold.
QDesign Music Compression (48 kbps bit rate), 100 kilobytes
MP3 Compression (48 kbps bit rate), 100 kilobytes
MP3 Compression (128 kbps bit rate), 256 kilobytes