The optimal sample rate at which to record is a matter of considerable debate. Proponents of recording at sample rates above 44.1 KHz typically claim that the higher frequencies yield greater detail. And while there’s a tradeoff – tracks recorded at 96 KHz need more than twice the storage space of those captured at 44 KHz – we’re assured that the increased detail means listeners hear more accurate recordings.
Don’t believe it. In recorded sound, accuracy is a myth.
Sample rate refers to the regularity with which a digital recording system checks its input for sound. Systems that sample more often can capture higher frequencies. An engineer named Harry Nyquist figured out the head-spinning math, and concluded that 44,100 samples a second, the rate used for compact discs, lets us record audio frequencies up to about 22 KHz.
This is 2 KHz beyond the accepted limit of human hearing, and in theory allows the capture of all the high frequency detail we can possibly hear. However, recent studies suggest that we are sensitive to hypersonic signals, even if they don’t register on our ears. Because of this, some audiophiles claim that recordings lacking these very high frequencies are less accurate.
In this context, accuracy is a myth, and it should be obvious to recording and mixing engineers why. The nature of our craft dictates that it is impossible to perfectly and faithfully recreate a sound source. We choose which gear to use for a given situation, and the properties of that gear affect how it colours any sound it records. Further, our mixes differ on every listening system, from the studio monitors to car stereos to iPod ear buds; and finally, the frequency response of human hearing is incredibly volume-sensitive, so individual listeners hear everything differently to begin with.
These are the facts of life for mixing engineers. We strive, then, to achieve “transparency” in mixes, in place of perfect accuracy. We want our mixes to translate well from system to system – never perfect, but always good. It’s an act of hubris on the part of a listener to assume that his $5,000 amp and $10,000 speakers will yield more accurate or perfect sound than what the mixing engineer intended. And this underlines an important point: Unless you deal with sounds captured through a single mic, every sound in a recording is the result of a mixing decision.
So the use of higher sample rates to achieve better accuracy is a flawed concept. However, that raises another argument often offered in favour of capturing high frequency content: “Even if most systems can’t reproduce the extra detail, the ones that can will offer an improved experience, so why not just leave it in?”
This line of reasoning makes sense for consumers eager to rationalize the month’s pay just spent on a power amp. But amateur mix engineers should know better. The argument that 44.1 KHz recordings are less enjoyable because of missing hypersonic frequencies relies on three assumptions:
- That the recording gear was sensitive to the desirable high frequencies,
- that the monitoring environment allowed the mixing engineer to make decisions about those frequencies, and
- that the mixing engineer is sensitive to hypersonic frequencies in an objective way, and included only those frequencies which enhance the sound.
There are certainly gifted (and fortunate) engineers who satisfy all three conditions. But before deciding to use a high sample rate, you must ask yourself honestly if you are among of them. In fact, unless you have the equipment to accurately capture and gauge high frequency content, and believe you can objectively mix the signal, the notion that “adding it can’t hurt” is antithetical to good mixing practice. Transparent mixing depends on making decisions that improve the mix. Every element of the mix should improve the final sound, or it’s simply not needed.
Adding high frequencies “just because” is equivalent to slapping a compressor on every track because you saw Butch Vig do it once. We all know this is bad practice. And the same rationale bears directly on the decision about which sample rate to use. Unless your equipment and skills are up to the task, tracking at 88.2 KHz or 96 KHz might damage your recordings.
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