Audiophiles and hi-end audio equipment are the subject of much controversy. Everyone seems to have an opinion, ranging from utter disbelief in anything audiophile to complete trust in whatever the manufacturers have to offer. Unsurprisingly, a lot of FUD and fables arose over the years on both sides.
I’ll try to provide a more or less moderate point of view in this article – along with a few facts from recent audio gear history and a primer on what this whole audio quality thing is actually about. I’ve been on both sides of the control room glass for quite a few years (you’d be surprised how many audiophile myths persist even in the pro audio crowd). I also have a penchant for good music and good quality sound, so I guess it puts me right on the fence. Disclaimer: I’m not a full-time engineer. Feel free to correct me.
Note that I’ll only be covering stereo – for several reasons. It’s 5.1 times harder to get room acoustics right with multichannel and there aren’t that many good albums out there in surround – as it’s also 5.1 times harder to mix a multichannel album! Besides, the greatest albums of all time of pretty much any music genre are stereo (or even mono).
Part 1: Earing the difference
Hearing is like any other sense in that it can be trained. It’s true that an experienced engineer can and will hear and identify both obvious artifacts (comb filtering, phase cancellation, etc.) and subtleties like differences between A/D converters. As with other skills – ear training is something that cannot be taught, it must be learned through practice over the years. Good engineers will familiarize themselves with the “sound character” (timbral qualities) of every piece of equipment they use.
Bear in mind though, that subtleties are just that – subtle. Quite easy to distinguish with a trained ear on a solo track, but in the mix it’s is a completely different story. The best example is real vs. sampled grand piano. Sampled pianos have gotten really good in the last few years, but it’s still relatively easy to tell them apart from the real thing – provided we hear the piano track solo. It’s much harder (or impossible) to tell the difference in the mix, unless the sampled version is really, really bad, like from a cheap rompler.
Many aspects of sound can be measured with extreme accuracy. The thing is, it’s difficult to precisely describe timbre. It’s all harmonics and partials, envelopes and modulation, and it can be sampled and represented numerically – otherwise, sound reproduction would be impossible. However, timbre is also a sensation. Subjective assessment and psychoacoustics (and, in many cases, psychology) have their say here. Mankind has only recently started to grasp the nature of timbre and some commonly accepted beliefs have already been proven false.
This is exactly why we have listening tests. The de facto standard is double-blind ABX testing. Double-blind means that neither the test subjects nor the researchers know what exactly is being tested. ABX is a method of introducing stimuli: A and B are alternatives and X is either A or B, but changes randomly between test iterations.
Note: there’s a story on how blind tests supposedly don’t work – a respected audio engineer purportedly discovered, in a ten-minute non-blind listening test, an artifact in a codec that passed 20,000 double-blind, triple-stimulus trials with hidden reference (as defined by ITU BS.1116) by 60 expert listeners at the Swedish Radio. I’ve seen this story quoted hundreds of times in print and on the Internet, sometimes by quite knowledgeable people. It actually comes from this article in Stereophile and there’s not a single piece of evidence available to corroborate it (other than “an audio recording played at (…) the 91st AES convention” mentioned – you guessed it – in the article). Even if it were true, it might as well mean that everybody had heard the artifact but the fact got lost in the average results.
All comparisons must be done at precisely matched levels. Human ears are sensitive to variations as low as 0.5 dB and louder sources are always perceived as better in direct comparisons.
Not all ears are alike: the standard human hearing range (20 Hz – 20 kHz) differs from person to person and decreases significantly with age (adults rarely hear above 15 – 18 kHz). What’s often missed, however, is that there are dips and peaks within the hearing range, e.g. a person may be less sensitive to frequencies around 4 kHz, while another person may have a sensitivity peak there, influencing perception of speech and music material in that range.
If you’d like to know your hearing range, take an audiometric test. Be aware that few facilities offer proper high-frequency audiometry (above 8 kHz). You certainly can’t use a tone generator on your computer to test: consumer sound cards can’t accurately reproduce very high frequencies. What you actually hear with that tone generator set to 20 kHz is just aliasing noise. Moreover, audiometric headphones have to be properly calibrated.
Using standard PC sound cards (particularly those in laptops) is a bad idea anyway for any audio-related testing. Apart from poor sound quality (cheap analog and digital components and an abundance of noise problems, especially at low listening levels) these cards usually have a built-in limiter to protect the speakers, so you may experience compressor pumping – unwanted audible gain changes. Many an engineer got bitten by this: the customers would listen to the mix on their laptops, hear severe compressor pumping and complain to the engineer, who in turn would not hear it on the studio setup. Turning down the level usually helps.
Let’s get back to audio gear. The usual hi-end audio setup is: loudspeakers set up in some kind of a listening room, connected to an amplification device (integrated or not) connected to a sound source, connected to a media transport (combined or not). I’m going to cover most of these components in the above order, as (to me) it is the proper order of the amount of influence on the overall sound character.
Coming up next: $10,000 loudspeakers – we won’t get fooled again (or will we?)