iTunes Music Store and Sound Quality
According to the rumor mills, Apple is in discussions with some record labels to sell higher-quality versions of the music it sells in the iTunes store. The store’s offerings are currently “CD-quality,” which for more than twenty-five years has meant digital audio captured at 44.1 kHz sample rate and 16-bits available per sample. Apple is looking to up that to 24-bit audio and will, I assume, charge people to upgrade their libraries much as they did when they switched from 128kbps to the current 256kbps they offer. I’ve been looking around and all the usual comments are popping up about greed, sound quality, the death of audio quality and quality music, the relevance of any of this with a public that almost solely uses crappy equipment to listen to music, and so on.
One thing pretty much everyone agrees with: Apple’s change from 128kbps DRM-encoded music to the current 256kbps non-DRM format was significant. Pretty much anyone can hear the difference on pretty much any equipment. In fact, some studies show that more people could tell the difference when the tests were done using low-quality playback devices such as earbuds and small speakers than with high-end gear. This certainly raises an interesting point for those who ask if audio quality matters when people are listening to earbuds and those on the other side who wonder why you would spend a lot of money on a good stereo. The conclusions are obvious: good-quality audio and good equipment make for better sound.
So what about the switch from 16-bit to 24-bit? My take is exactly that: so what, at least mostly. For the vast majority of recorded music, 24-bits is a non-issue, for one. Anything recorded using less than 24-bit technology will see no gains at all. The source material is fixed and cannot be improved upon. This basically means that for everything recorded before about 1997 (release of ProTools 24-bit) and even for most mainstream releases recorded after that until very recently, there will be no inherent benefit going to 24-bit.
Now, some material will certainly be remixed and remastered and sound better, but even in those cases the majority of improvements, if there are any, will be from artistic choices and not from increased audio quality. So don’t rush out and download the whole Rolling Stones library again just because it’s 24-bit. When they recorded Sticky Fingers, for instance, the state of the art allowed for about 75db dynamic range in the studio and around 60db on a mastered LP. That doesn’t even push 16-bit technology to its limit, and that was the maximum, in practice.
Most recordings use much less dynamic range than the maximum available. And that’s something to realize: it’s only in extremely dynamic material recorded natively in 24-bit that the 24-bit material will be perceived as superior to the listener. A Ferrari and a Jetta both get you home at the same time if you drive 55 mph. And then of course come all of the usual arguments about earbuds and small speakers, and that while 256kbps sounds pretty good with 16-bit, it will likely have a bigger effect on 24-bit recordings, and so on. If Apple really wants to improve things, they should start offering everything in uncompressed 16/44.1. That would certainly be a real step forward.