High resolution audio: myths and realities
High resolution sound is in vogue. A good part of the manufacturers of music equipment, and more and more record labels, especially those that sell over the Internet, seem determined to convince us that high-resolution audio is what all of us who love music should aspire to if We want to enjoy it with the highest possible quality.
On paper there are technical foundations that justify the existence of high resolution audio and indicate that its quality should be higher than that offered by the CD. But there are also solid reasons that invite us not to take their superiority for granted, at least not in such a clear way, and to question some of the virtues that the industry sells us. Let’s see what high resolution sound is, what we need to enjoy it, and, above all, if it really offers us a better experience than music with standard quality (that of the CD).
What is high resolution sound?
To understand in a simple way what high resolution sound offers us, it is good to review how music is stored on CDs that we all know. These discs, unlike vinyl, allow us to store information in the digital domain, while vinyl discs are analog. This means that the music on a CD is encoded in the form of ones and zeros, in exactly the same way as the information we have on the hard drive of our computer, which is also digital.
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IN XATAKA
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But a CD does not have an infinite capacity; in fact, the size of the tiny notches that we see on its surface if we look at it with a microscope and the distance that separates each one from the adjacent ones reveals how much information it is capable of holding. Precisely, in a simplified way, this is what differentiates the CD, the DVD and the Blu-ray Disc: the size of the small holes that encode the information and the distance that separates them. If we compare two discs with the same diameter, the one with these smaller notches and more together will have more capacity. This parameter is precisely what determines the wavelength of the laser that we must use to extract the information.
Formats
The technology of the CD format was developed at the end of the 70s by Philips and Sony, and it was the engineers of the latter company who proposed to encode the information using a resolution of 16 bits and a sampling frequency of 44.1 kHz. But these figures were not chosen at random; These specifications allow this format to reproduce the sounds that are in the frequency range that goes from 20 Hz to 20 kHz, which coincides quite accurately with the frequency limit that the human auditory system is able to perceive, even bearing in mind that Not all people have the same hearing ability.
The CD uses a sampling of 44.1 kHz to, according to the Nyquist-Shannon theorem, be able to reproduce frequencies up to 20 kHz
To understand what is the resolution and the sampling frequency without going into too cumbersome details we can think that to be able to store an analog signal, and, therefore, continuous, in a digital medium, which has a limited capacity, it is essential « Chop up that continuous signal into small fragments, or samples, and introduce as many as fit into the digital medium. The resolution indicates the number of bits that we can use to describe each of these samples, which, in turn, reveals the number of variations or possibilities that each of them can adopt. And the sampling frequency tells us how many we are going to be able to take.
(Part 1)
