Over the nearly 40 years I've been in this business, measurement of audio systems has evolved from a crude, often hugely inaccurate and amazingly complex pseudoscience into an often complex but supposedly far more accurate science.
The early devices, clearly primordial and archaic when compared with today's computer based DSP filter-equipped technology, almost always depended solely on the skill and knowledge of the user to provide any remotely viable results.
If you were lucky you got sort of 1/3-octave spectral information, maybe some reasonably close-to-accurate analog metered voltage and current results (Try being precise when reading a moving analog meter), and perhaps some kind of oscilloscope-based (interpretable) measurements.
Ever since the introduction of TEF-style measurement in the early 1980s the amount of "higher" precision of data has escalated logarithmically. Add in the computer based simulation and acoustical performance prediction software, and you can now produce enough data and graphics to convince any client that you know what you are doing.
The problem is that data quantity is not sufficient grounds to believe the information. Just because you have hardware and software that can tell you to within a fraction of a decibel precisely how much energy exists at some precise point in space doesn't mean squat! The ready availability of such tools means that far more often than not enormously unqualified people are collecting truly useless data and applying that data to the "correction" of sound systems of all types with no understanding of what they are doing or what the information they so accurately collected really means.
The number of systems that have suffered from this process is so large that it has become an unspoken rule of thumb that once a system is "measured" it often sounds worse than it did before all the technology was applied to its tuning.
Now don't assume I'm being a luddite and rejecting analysis tools and the data they produce in favor of just "using your ears," as some have aggressively suggested.
The number of individuals alive who can effectively perform such work is microscopically small compared with the number who claim they can. It takes years of practice and experience to even know what to listen for, let alone apply that knowledge.
So it's a given that some kind of measurement tools will have to be used. The question is how to use them and whether or not the resultant data is helpful.
From my perspective none of the currently offered measurement systems can be used without some training and understanding of the information being presented. Even those that largely automate the data collection and interpolation process still require the user to know what they are looking at/for and then what to do with the information. Unfortunately the number of units acquired is far larger than the number of people who have bothered to take the training or think they don't need it.
On some systems, even a minor setup error or the choice of the wrong parameter set can so distort the data as to make it beyond useless. Yet this kind of mistake is so easy to commit that it happens to even the experienced users more often than they will admit.
Thank the deities that we're not in the medical profession, because if we were the simply erroneous data we collect and "interpret" would be killing people. Think what would happen if your CAT scan specialist mistook that blob for a tumor and caused you to have surgery, when it was merely a defect in the screen or imaging software - I can hear the lawyers salivating.
Lucky for us that the legal profession hasn't yet marked us as a target for these kinds of mistake lawsuits, but I believe it's only a matter of time before some high profile facility does sue and win.
We seem to have fallen into the scientific-grant/government-funded study mindset wherein the data itself is the goal - not data that is useful or appropriate or even valid, just mounds and reams of data for its own sake. At an Acoustical Society of America convention you could scan the program and find dozens of papers that exist solely because there is data to present. In fact many of the projects reported on breathe because they produce data - not data anyone needs or even data that could be used in some positive way, just slaughtered forests worth of data.
Many years ago one of the early pioneers of precision measurement said to me that he could tell me that there was a 7.32456098dB bump in the response at 8.2459876kHz caused by the knobs on the console in a control room, but he couldn't fathom what use that was or why I would want to know since there was nothing that could be done about it.
Unfortunately he remains in the minority with that viewpoint, since useless data and data that is just plain wrong is being produced by the metric ton every day.
I'm glad I don't have to wade through that swamp of numbers, but the industry does. Maybe when all that technology can give me information I can use, I might start believing some of the rest.
Note: There are one or two systems out there that have focused on producing data that provides real answers. Regrettably they are often hidden by the effluent from the many others that don't.
About The Author
Ampel holds a Master of Science Degree in Engineering from Boston University, and a Bachelor of Arts in English/Music from Long Island University. He has been published in the proceedings of the IoA, AES, NSCA, InfoComm and numerous journals and publications. He currently writes feature material for Residential Systems for which he is also principal editorial consultant, and contributes to LiveSound International. He was the principal editor for the 1997 edition of CEDIA's Home Theater Manual. Ampel served on the AES' SC10 committee on Computer Control of Audio Systems and both the NSCA and CEDIA education committees. He also chaired CEDIA's Certification Task Force. He has conducted classes, workshops, and papers sessions for NSCA, CEDIA, InfoComm and AES, as well as the IoA and SCIF in the UK, and several trade events in Hong Kong, Singapore and Australia. He is an active member of AES, ASA, CABA, CEDIA, IoA and NSCA.
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