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.
Nice to see a scientist here. :) You bring up a lot of the processes that are important in making certain claims about desirability, and that these are ultimately statistical not personal measures. There’s a big difference between measuring THD+D and subjectively measuring listener preferences for different values and mixes of harmonic distortion as pleasurable/desirable or not. The work you describe IS science. Blindly taking a measure and claiming it ideal is not. |
@jakleiss , this is an interesting approach. Have you considered segmenting the market of audio device consumers? I'll bet the research shows different preferences for each segment.
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Yes, it is science. My professional career has been providing scientific evidence to inform product design, most recently in healthcare. The FDA requires scientific evidence to support any claims one may make about medical devices and treatments. That includes health benefits, but, also, such things and ease/safety of use and patient experience. |
kota1, As to segmentation, yes, I have done a good bit of that as well. There are the typical factors such as age, gender, education, and culture. But, people just differ from one another in their individual preferences and sensibilities. Those differences are easily reflected in different profiles of the perceptual scores I mention. |
@jond, I was a bit loose in my use of the term "like" as that only describes the Valence component of perception. In reality, people in the Sensory Sciences often only use that one component. I like the full perceptual profile, so "Preference" might be a better term. The point, however, is that the science provides knowledge of the physical properties of the system that are most strongly associated with each individual perceptual component. Knowing that enables choosing a product for listening whose metrics are most closely aligned with preferences. Ultimately, you do have to listen, but the science helps you weed out the chaff before listening. I often begin a study by having the participants rate their imagined "ideal" (i.e., preferred) product. That provides a criterion against which to compare the actual products being evaluated in the research. It often happens that different individual products exemplify ideal levels of different psychological components. Hence, the "ideal" product for a given sample of listeners may not yet exist. The challenge for designers and engineers is to combine those separate features into a single "ideal" product. I want to emphasize that the research informs group tendencies. However, the statistical nature of the data allow you go backwards and specify for a given perceptual profile, what physical metrics correspond to it. Doing so gives you a head start on choosing a system for listening, which is the ultimate arbiter of quality for you. |
Well, Doctor, I think you got it right. We are listening to the art of recorded music and playback, not the real thing. |
russ69, I like your phrase, “…the art if recorded music and playback.” It’s sort of like cooking. You mix the audio ingredients in such a way as to produce a preferred “flavor” of audio experience. People aren’t actually as different from one another in this regard as you might think. Opinions differ a great deal, but psychometric measurements are remarkably reliable. So, manufacturing a broadly “preferred” is feasible. This should be the aim of the manufacturers. |
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. |
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. |
OP: The goal of audio reproduction. Wow! Seems intolerably myopic in scope. The OP constructed a gross assumption of confined utilization. What about those who enter car audio contests in which the parameters are simply bandwidth and decibel pressure? Or the house party where paint peeling is the sport? There is the ulterior motive of setting a romantic mood with Barry White. How about music to prepare a 5 course Italian meal by? The military bombarded a certain Panamanian dictator with music to get him to give up. Sports venues utilize selected pieces to loudly motivate their fans and team. Or, I could be completely wrong. That's happened before. Whew. Let the rage begin.
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