The goal of audio reproduction


I have followed the ongoing exchanges regarding subjective versus objective criteria for audio quality for some time now and finally wish to toss in my 2 cents. I am a Cognitive psychologist and have spent most of my professional life conducting research to measure how consumers and users of products perceive those products. I use formal psychological measurement techniques to quantify perceptions. In essence, I "objectify" subjective experience. So, the subjective versus objective distinction is, to me, somewhat misconceived. Given that perceptual experience can be measured (objectified), I would say the important question is, what physical features of products (i.e., physical audio metrics) correlate most accurately with perception? A more valid distinction, to me, is the distinction between "effective" (something of a causal nature) versus "affective" (i.e., something of an emotional nature). Objective product metrics "effect" subjective perceptions (affects). It's stimulus/response psychology.

I use multivariate statistical techniques to model effect/affect (i.e., stimulus/response) relationships. Here, it is important to consider that perception (i.e., affect) is not a single thing, but a composite of multiple factors. These include a) Valence (the standard good versus bad distinction, b) Potency (strong versus delicate feeling), c) Arousal (intense versus mild feeling) and d) Novelty (familiar versus unusual feeling). Hence, a complete description of perception requires a profile of these four perceptual components and not a single concept such as good or bad.

It is also important to note that perceptual data such as described above are obtained from samples of typical product users not from one, or a few, experts. Trained experts may be used in perceptual research, but their role is simply to describe the subtle perceptual qualities of products that may elude measurement. Experts serve as biological test instruments (very common in food, beverage, and cosmetics industries). But they don't serve as surrogates for typical consumers of products. For that, perceptual data are obtained from typical consumers. And those data are not expressed in terms of perceived physical properties of products, but the psychological responses to those physical properties.

The upshot of this for audio (it seems to me) is that if you just want to replicate a particular auditory event (e.g., a musical performance) then matching all physical metrics of the reproduced performance to the live performance is fine. But if you want to produce an enjoyable audio experience you might find that certain physical properties affect listener's perceptions more or less than others and that a departure from veridical presentation is preferred. For my part, I think that is fine. In fact, I am finding my tastes in audio quality are changing somewhat and I am now drawn to a slightly different quality in my system. I don't care if it matches the real performance exactly. I care that I like it.

jakleiss

mastering92, 

Actually, I'm not proposing to strive for absolute fidelity to the original recorded material. Rather, I'm suggesting to play it back emphasizing those qualities that are preferred by the listeners. This might involve enhancing certain physical qualities in the played back material, or suppressing certain other qualities. The important point is to do that based on the preferences of a target sample of listeners. Our symphony in Milwaukee just moved into a new venue with much improved acoustics. Listening in either venue is absolutely realistic, but they are not equal in their sound quality. 

@jond 

I don't need science to know that I like something. I need science to know why I like it. Humans are particularly unreliable at pinpointing the physical causes of their perceptions and emotions. This issue should really be of greater interest to designers and manufacturers of audio equipment than individual listeners. It's the manufacturer who has to make things that a large enough number of people like to warrant the expense of manufacturing them.

Hey @jakleiss understood I was just gently poking fun and as I said in my post it sounds like a very thought out and reasonable approach.

Thanks for the clarification, jond. "Fun" is a subtle property in this communication medium. But, my point is important nonetheless. The issue of what is most liked, and why it is liked, are two different things. That is why the "sensory" industries such as food, beverage and cosmetics address them separately. They don't trust consumers to tell them why they like something, only how much they like it. They correlate liking with various physical properties in a separate phase of research to understand what is causing the liking. This is of particular interest to manufacturers, who want to reproduce liking.