Speaker Reviews - Are They Adequates?

[Chu Gai]

OK, here's another thing. There are reviewers that not only make some of their bread and butter reviewing speakers but also wires, cables, and sundry tweaks. They're hard core enough that when they buy stuff for their own personal use, they'll buy these product (probably after a significant discount from the vendor). In the case of speaker reviews, can their opinion be trusted especially after they wrote how they tried this wire and that?

 

[KARRI acoustic]

If I could chime in here as a designer and manufacturer.

If we can start with the a priori assumption that providing the most perceptually accurate recreation of the recorded event is of utmost importance, as I believe it is, then there is a truth that must be appreciated that there is currently no measurement or set of measurements that will specify the extent to which a loudspeaker achieves this. There is knowledge within the field, and some differing opinions in regard to importance and implementation, but no universally agreed measurement specification that encircles 'necessary and sufficient'.

Some groups such as Harman have done good research in showing predictability in preference based on a combination of on and off axis measurements, and particularly for smooth acoustic power curves. These curves are one good set of measurements, as are CSD plots. They don't, however, tell the full story.

It must be kept in mind that the goal is successful perceptual recreation. A good way to illustrate this, for those who have had the experience, is to listen to a loudspeaker in an anechoic chamber - it is my wont in designing speakers, but certainly not for listening to them! We now arrive at differing philosophies - and I must call them that as we don't yet have sufficient knowledge to call them a sufficiently developed science, although they should always be grounded in science. One manufacturer may prefer the monopole radiation with its side reflections, whereas another (such as us with our current line) believe that dipole radiation is better in minimising deleterious side reflections while maintaining the balance and timing of reflected sound necessary for convincing recreation (in the case of a dipole speaker, by keeping a somewhat 'live' back wall).

How important are these currently poorly defined aspects of sound recreation? Some research in perception suggests very much so. If a microphone is placed so as to record the sound reflected into the ear canal from the pinna and then played back to the proud owner of that pinna then spacial awareness is well maintained. Play it to another person and it is confusing. What does this tell us? In regard to loudspeaker design, a little bit. It tells us that the way that sound reaches the pinna and is reflected into the ear canal is important. If we once thought that simply relying on two loudspeakers to recreate the direct and ambient sound of the event could be convincing, we should by now be having our doubts. Our auditory perception is more highly attuned than to be so easily fooled. We arrive back at the dreaded 'compromise' - we can't recreate the correct reflecting proportions for every sound source and venue, so we find a compromise that is adequately convincing.

So, now I've indulged a small area of my field of expertise, if we circle back to the topic then where does this leave us? Probably with a set of measurements supported by subjective commentary on how 'vividly' or 'naturally' recreated the sound is.

 

[Floyd Toole]

Hello Karri,
You said: "the goal is successful perceptual recreation". This is absolutely true, but the question is: recreation of what?
Stereo - two channels of information - are simply not adequate to capture and reproduce anything resembling the "real" sound field that might exist in live performances. I spend many pages of my book "Sound Reproduction" explaining that only multichannel schemes can even approximate that.

Stereo recordings are mixed and artistically tweaked while listening to two (non-standard) loudspeakers in (non-standard) control rooms. Everything we hear, starting with the basic timbre of the sounds through the imaging and sound stage are manipulated to sound good at the point of creation. Since none of this is standardized, recordings vary enormously, and none of them are "real". The best that can be done is to convey a few strong clues to what might be real. The rest is in the mind of the listener. In this situation the recreation that we seek is the sound the artists and recording engineer heard in the control room - that is the "original performance", but we don't know what it was.

Of course, adventurous audiophiles go further, trying to inject some of the missing information. Over the years a semi-infinite variety of loudspeaker designs, electronic manipulators and acoustical devices have been created to try to fill the void between what is in the stereo signal and what the listener would really like to hear. All succeed and fail to varying degrees because the original stereo system is so seriously deficient in directional and spatial information. The movie industry realized the importance of spatial information decades ago - the latest "immersive" audio systems have channel counts ranging up to 64 - not two. I have heard music in a couple of these systems and it is stupendously realistic - you can stand up and walk around as if you were in a concert hall or cathedral. The music industry has demonstrated that it is interested only in delivering a melody, lyrics and a foot tapping rhythm. All else is optional, and less than is needed to generate a "successful perceptual recreation" of a live performance. The public at large seems not to care much, leaving those of us who do care out in the cold.

My recent lecture covers some of this, addressing the recording industry:

My recent paper in the Journal of the Audio Engineering Society addresses the lack of meaningful standardization in the audio and movie industry - go to aes.org, click on Publications then "open access" and type in my name. The 30-page paper is a free download to anybody.

Cheers, Floyd

 

[Irvrobinson]

Stereo - two channels of information - are simply not adequate to capture and reproduce anything resembling the "real" sound field that might exist in live performances.

For reproducing large venues, like a concert hall, in a residential room, I completely agree. The illusion of the large venue is unconvincing; you get only hints. For recordings made in small performance venues I think your statement is an exaggeration. I make my own two-channel recordings of small ensembles and solo instruments and the playback is very convincing. In the case of a flutist playing along with a recording of herself the reproduction is surprisingly close.

 

[Floyd Toole]

Irv,
Good for you, because you are closing the "circle of confusion" by making recordings specifically for reproduction in your room with your loudspeakers. A small ensemble can be construed as performing live in your listening room, and only minor additional "ambiance" might be needed. I would be surprised if it did not work to your satisfaction. But this is not the state of the general audio industry, nor the normal manner in which recordings for the mass market are made. That is the problem.

 

[3db]

Hello Karri,
You said: "the goal is successful perceptual recreation". This is absolutely true, but the question is: recreation of what?
Stereo - two channels of information - are simply not adequate to capture and reproduce anything resembling the "real" sound field that might exist in live performances. I spend many pages of my book "Sound Reproduction" explaining that only multichannel schemes can even approximate that.

Stereo recordings are mixed and artistically tweaked while listening to two (non-standard) loudspeakers in (non-standard) control rooms. Everything we hear, starting with the basic timbre of the sounds through the imaging and sound stage are manipulated to sound good at the point of creation. Since none of this is standardized, recordings vary enormously, and none of them are "real". The best that can be done is to convey a few strong clues to what might be real. The rest is in the mind of the listener. In this situation the recreation that we seek is the sound the artists and recording engineer heard in the control room - that is the "original performance", but we don't know what it was.

Of course, adventurous audiophiles go further, trying to inject some of the missing information. Over the years a semi-infinite variety of loudspeaker designs, electronic manipulators and acoustical devices have been created to try to fill the void between what is in the stereo signal and what the listener would really like to hear. All succeed and fail to varying degrees because the original stereo system is so seriously deficient in directional and spatial information. The movie industry realized the importance of spatial information decades ago - the latest "immersive" audio systems have channel counts ranging up to 64 - not two. I have heard music in a couple of these systems and it is stupendously realistic - you can stand up and walk around as if you were in a concert hall or cathedral. The music industry has demonstrated that it is interested only in delivering a melody, lyrics and a foot tapping rhythm. All else is optional, and less than is needed to generate a "successful perceptual recreation" of a live performance. The public at large seems not to care much, leaving those of us who do care out in the cold.

My recent lecture covers some of this, addressing the recording industry:

My recent paper in the Journal of the Audio Engineering Society addresses the lack of meaningful standardization in the audio and movie industry - go to aes.org, click on Publications then "open access" and type in my name. The 30-page paper is a free download to anybody.

Cheers, Floyd

I have never been fortunate enough to sit at a recording session let alone listen to the finished product on studio equipment. (That would be a very humbling experience. ) So when I listen to the recording at home, I have really no point of reference to see how close it comes to the source. On the other hand, I've been to concerts, both classical music and rock and in some cases, I would prefer the stereo recording over what I actually heard in some of those venues as the acoustic smear was just horrid. Maybe the music was played to loud for the room.

 

[Irvrobinson]

I've been to concerts, both classical music and rock and in some cases, I would prefer the stereo recording over what I actually heard in some of those venues as the acoustic smear was just horrid. Maybe the music was played to loud for the room.

That is such a common problem. Massive PA systems and huge amps are within the financial reach of even amateur musicians, and with wireless mics everything gets amplified, even loud instruments like drum kits and saxophones. It's just stupid. My wife was in a band a couple of years ago that had a bandleader (the lead guitarist) I fought with all the time. He liked everything really loud. I always wore earplugs. One night I brought along my handheld meter and found their average sound level at 30 feet or so (I wouldn't sit closer) was about 102db. I've learned that you can be a great musician and still be as dumb as a rock.

 

[3db]

For rock concerts, over amplification for the venue seems to be the norm unfortunately. The classical concert I was referring to Beethoven's 9 where the choir (at least 150 people strong) was louder than the orchestra....which I don't think should be the case. I felt that the choir overwhelmed the stage.

 

[Irvrobinson]

Irv,
Good for you, because you are closing the "circle of confusion" by making recordings specifically for reproduction in your room with your loudspeakers. A small ensemble can be construed as performing live in your listening room, and only minor additional "ambiance" might be needed. I would be surprised if it did not work to your satisfaction. But this is not the state of the general audio industry, nor the normal manner in which recordings for the mass market are made. That is the problem.

Just to be clear, IMO, it does indeed obscure the realism of the recording somewhat to hear the acoustics of the room twice during playback. This is clearly audible with a piano in my room. Nonetheless, I believe one can get close enough to sounding live that the experience can be quite thrilling, if one's objective is realism.

I have also been surprised at how easy it is to make excellent-sounding recordings. Not so long ago I tested out a new Tascam handheld digital recorder just by setting it on the edge of a coffee table, with the microphones protruding a bit, and having my wife jam on her drum kit. I wasn't even trying to make a good recording; I was just testing the unit to ensure it worked. I was astounded at the results. My system can't quite reproduce a drum kit to the point where it is indistinguishable from the real thing in a residential room, but I haven't taken out my more ambitious mics and mixer for a small venue since. My one improvement is to put the recorder on a stand.

It does make me wonder how the pop music industry can screw up recordings so much in $1M+ studios. I couldn't agree more on the general state of the audio industry, though the classical and jazz genres are much better than popular music.

 

[3db]

Irv,

If you like blues, I suggest picking up this album. Its a well produced album and it brings out the best in my system.