Digital audio fidelity

Take the following two hearing tests while wearing high-quality over-ear headphones connected to a high-quality sound card:

The first tests your ability to hear sound of different frequencies. Older people will be doing well if they can hear up to 15 kHz. A lot of older people can’t even hear up to that; in one ear I can hear 10 kHz and I think I can hear 14 kHz in the other.

The second tests your ability to discern audio quality (quantisation and sample frequency). My score was 33%!

Those tests are eye-openers. My family did a lot better than me, especially the younger members. One of them could hear above 20 kHz in the first test, and scored 100% in the second test (which is exceptional because all the others scored 50%, so even young people struggle to hear a difference).

Even with my poor hearing I can hear how bad a 128 kb/s mp3 music track sounds, but when you get up to 320 kb/s it’s a different matter. In most cases I can’t hear the difference between 320 kb/s and a 16-bit 44.1 kHz Audio CD, and, as the tests in the above links demonstrate, most people struggle to tell the difference too (watch the video ‘Audiophile or Audio-Fooled? How Good Are Your Ears?‘).

Regarding sampling theory, the video ‘Digital Audio: The Line Between Audiophiles and Audiofools‘ is quite good if someone does not understand why 16-bit 44.1 kHz was chosen for Audio CDs. As to finer quantisation and higher frequencies, ‘The Difference Between 24-bit & 16-bit Audio is Inaudible Noise‘.

As to the perennial discussion regarding CD audio versus vinyl audio, an audiophile friend of mine with a life-long passion for hi-fi has an insanely expensive hi-fi system which is integrated throughout his house – including a room designed exclusively for listening to music – and controlled via iPads, with hand-built pre-amps imported from a small, specialist manufacturer. His main speakers alone cost a lot more than most people pay for an expensive sound system. He switched to dedicated music servers with uncompressed (FLAC and WAV) files either purchased directly or copied from well-produced 16-bit 44.1 kHz Audio CDs, and got rid of his expensive top-end record deck.

As for legacy physical media, Audio CDs are more vulnerable than vinyl. Some of the Audio CDs I bought around 20 years ago have already suffered the well-known phenomenon of disc rot despite being carefully kept and handled. Optical discs are rubbish from a longevity point of view. Vinyls, on the other hand, if kept in a controlled environment, will last almost indefinitely: ‘Record collector builds world’s largest vinyl hoard – six million and counting‘.

However, much as I love LP artwork I’d rather have my friend’s digital system any day. Even with my degraded hearing the music it produces sounds fabulous. Not to mention that the slightest click from a dust particle in an LP groove is, to me, akin to nails scraping on a blackboard. Those were the days!

About Fitzcarraldo
A Linux user with an interest in all things technical.

2 Responses to Digital audio fidelity

  1. viewinghood says:

    I have video and audio optical discs of the size of a big vinyl album called LaserDisc.
    The ealiest discs are from NASA and from StarTrek (TOS) and were made in the late 80th…
    The audio coding is mostly high quality PCM. The video is analog coded and from the perspective of color shading much better than DVD 😁

    • Fitzcarraldo says:

      Nice. I didn’t mention the various other optical disc audio technologies such as DVD Audio and Super Audio CD (SACD) which were intended to improve on Audio CD. I still have my DVD Audio player that plays 24-bit 88 kHz 5.1-channel Surround Sound, but the benefit of the increased bit depth and sampling rate over Audio CD is debatable for the reasons explained in my post. What is an improvement over Audio CD is the 5.1-channel Surround Sound, which certainly adds to the listening experience if one has a) the hi-fi equipment to do it justice and b) a dedicated room to listen to it with the speakers positioned properly and the appropriate furniture. Not many people can do that, though (I certainly cannot). DVD Audio and SACD never really took off in a big way, and these days they are a very niche market.

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