The iPod's low bit-rate has come under fire – as are Apple claims that iTunes Music Store customers get "true CD audio".

The New York Times advises: "Love the iPod, but don't jump too hastily to fill it with thousands of dollars of iTunes. The tracks are not carbon copies of the CD originals, but compressed versions.

"The smaller files are handy for speedy downloads, space-saving for storage and perfectly serviceable for listening through ear buds when riding on the subway. Not what you will want, however, when your desktop computer becomes the home jukebox and wirelessly sends these simulacra to the entertainment centre in the living room."

In order to create a small file, Apple uses "an extreme form of compression that takes a sample of the sound at intervals," explains the report.

"The bit rate for iTunes, 128, is so low that when played side by side against the original, the difference is audible not only to audio enthusiasts, but also to mortals with ordinary hearing," reporter Randall Stross claims.

Apple spokesman Derick Mains disagrees. He says: "128 provides good sound quality, especially when used in iPods. The majority of people have absolutely no idea what a bit rate is. If Apple offered music encoded at a bit rate higher than 128, customers would select it without realizing that it would fill up their hard drive and portable player quickly."

Stross indicates that customers of the iTunes Music Store are led to believe that they are getting a CD in all respects except the trouble of going to the mall. "The iTunes store does not warn about the permanence of its method of compression; once freeze-dried, there is no way to reconstitute the music into CD quality for playing through a good stereo," he notes.

Although Apple claims to offer lossless data compression, which it says gives users "the full quality of uncompressed CD audio using about half the storage space," this is only available from shop bought CDs. The iTunes Music Store does not offer "true CD audio," Stross concludes.