What Is Sound Quality and How Is It Judge

I have been really thinking this subject through quite a bit for a while.  Here is a quick description on my take on the whole "SQ" thing:

I personally think there are two different types of SQ. There is subjective SQ and objective SQ. Objective SQ is trying to achieve the closest reproduction to the original source material as possible (hi-fidelity). This means that there is no distortion added and the frequency response is flat. Subjective SQ is what we prefer. I believe people like their music to be a little surreal. Whether this includes boosting frequencies that are lost to their ears due to hearing damage, or adding distortion to give the music a warmer sound (tube amps).

Steven Kephart

Adire Audio

To be honest, I haven't come to a full conclusion on this topic.  I know that frequency response will effect the soundstage and imaging.  You need a flat response to gain this.  But I also know that my boss doesn't voice our speakers perfectly flat.  He and his partner, Dr. David Hyre, spent thousands of hours listening to different popular frequency responses till they found the best fit for the most people.  Now the target this response with all their speaker systems. 

But at the same time the whole live event thing comes up.  Sure we may like our surreal experience at the time.  But why is the live play so much better than the movie?  Why is the live music so much better than the tweaked reproduction we enjoy at home?  If we had a speaker system with a perfectly flat response from 1 Hz to 100 kHz, 0 distortion, perfect phase response, somehow negates all room effects on the sound, etc. would we still enjoy the speakers more by tweaking it for the above mentioned reasons? 

Also, what bad things happen to the music when we do tweak it?  There is a great deal of information in music that is very subtle providing ambiance, imaging cues for depth and position, etc.  Well what if that instant gradification we obtain by making that tweak effects the listening fatigue of the speakers, and so we don't enjoy it as long.  In other words, what if our short term satisfaction from the tweak unconsiously effects our long term enjoyment? 

My boss has done a great deal of study on how distortion effects our listening, and what the differences between the types of distortions are.  He had a long dinner with Dr. Earl Geddes and his wife Dr. Lee (I can't remember her first name).  Dr. Geddes has his doctorate in acoustics IIRC and his wife is an audiologist where she studies the human ear.  Here's a link to their site: http://www.gedlee.com/   Basically they have found that it isn't the total distortion that is bad, but mainly odd order distortions that sound the worst.  Unfortunately physics guarantees that you can't completely eliminate all forms of distortion in a speaker.  We have brought to market a great technology that greatly reduces the more intolerable distortions.  But we have found that some don't like our speakers sound because they are used to the distortion that we eliminated.  It doesn't sound as "warm" to them.  However we feel that it is better to eliminate the distortions for a reference point, and then tweak from there if you really want to.  You can start from reference and move backward (add distortion, tweak the response).  But it is much more difficult (and sometimes impossible) to go the other direction.

Steven Kephart

Adire Audio

Ah yes, the old technical response VS audio perception can of worms.

Most people do not like the sound of flat frequency response.  That's one of the reasons the old RIAA equalization curve was created: to re-introduce and emphasize those frequency bands most people say are "missing" in a "flat" curve as well as to cut or de-emphasize those most people find harsh.  It's why pre-amps have "loudness" buttons and tone controls: to allow the listener to manipulate the sound in ways that both compensate for deficiencies and "colorations" in the reproduction equipment and to create colorations the average listener finds more pleasing.

It is not "distortion" that makes a sound warm or cold or neutral, it is the emphasis placed on certain harmonics from the musical fundamentals.  The difference in sound between a clarinet and an oboe is due to such harmonics.  It's what creates the "quality" of a sound.  Pure tone sounds "bad" and "mechanical" to the human ear and we do not like them.  That's why tubes tend to sound "better" to most people: they emphasize harmonics in ways more natural and pleasing to the human ear than can more accurate and "cleaner" amplifiers.

Audio design is a careful response dance between accuracy and manipulation.  It is impossible for any audio gear - and especially impossible for loudspeakers - to not add coloration and manipulation to a sound.  Anything that passes a signal will add something of its own character to that signal.  The key in good SQ, I believe, is to minimize those "additions" and "colorations" and to control those inevitable ones such that they tend toward what pleases the intended audience.