Unless you been living off planet or in a remote village in Northern Siberia, you probably are aware that there are literally dozens of software packages and tools to measure the performance of any sound system,
You can get these for your laptop, PDA, iPhone, smartphone, or almost any hand-held device with a sufficiently accurate screen resolution. Some are even free. What those are is for another blog, however.
The topic here is not the hardware or the software, it’s what you do besides gathering the actual data.
Now let’s be clear about one thing. YOU MUST have reference data on the sound system in question BEFORE you do anything else. (Reference data would include frequency response in at least 1/3 octave format, SPL data and the InfoComm/ACU Coverage Uniformity Standard data set: ANSI/INFOCOMM 1M-2009, Audio Coverage Uniformity in Enclosed Listener Areas. ) Without a benchmark of where you are, making any changes, fixes, adjustments, alterations, etc., is flying blind.
Even more importantly, the data you gather must be done using a system that allows repeatable, reliable measurements to be taken so that you can evaluate the results of your work and any “improvements” you make implement. Remember you (or whoever is doing this process) are not just taking one measurement, but probably dozens before you are finished.
One often misunderstood point on gathering data using a device like an iPad or iPhone is that the built-in microphone is nowhere close to being accurate enough for proper data collection. It is optimized for speech pickup and probably costs around 10 cents. Get an external mic preamp and a decent measurement microphone to hook up to your portable device. The total cost of these items can be less than $100.
Whether it’s called commissioning, calibration, tuning, equalization or any other descriptive term of your choice, the need to collect and collate data sets is not a debatable point.
BUT, the data alone is not the complete picture of what the sound system is delivering to the people in the room. In fact it’s missing a crucial ingredient: human perception, or the subjective portion of the total result.
Whether your measurement microphone(s) cost $100 or $10,000 they are still microphones, not ears. NO microphone, even the high-dollar human head simulators and similar devices, can precisely match the human ear-brain interface’s results. They can get extremely close, but close is simply not going to sign a check!
The point is really quite simple, and often so obvious that it gets forgotten. PEOPLE are going to use this system, and PEOPLE are going to be using their ears to evaluate the results of your work. You can stack up a forest’s worth of measurement data, beautifully presented in high definition, full color, but it’s what their ears tell them they are hearing that really matters in the end.
So you need to spend significant time “listening” to the system, before, during and after the technology has been brought to bear. This is where your knowledge and skill can be showcased, and more importantly where you can bring your experience into the picture.
There must be a correlation between what you measure and what you hear. If that is not the case then you need to back up and determine where the discrepancy is occurring and WHY.
Yes, there are something’s that even the most sophisticated measurement platform may not display, or at least not display it with sufficient accuracy to match what you hear. Albeit those are not common phenomena, but they do exist.
Since ears and making the final judgment, you need to train yourself to listen objectively and subjectively. You must be able to trust what you hear. Your customer, end user, client is not going to understand the technical data in most cases, they are simply going to base their evaluation on the acoustic envelope created by the room and the system together.
Training yourself to listen “scientifically” is not hard, it just takes a commitment and some time. Choose several systems that you know are producing quality results and with which the users are happy and comfortable. Take your measurement tool and your ears and put both program material and pink noise type test signals through the system and watch the data display and listen carefully. Correlate what you are seeing with what you are hearing — that is, calibrate your brain.
It won’t take all that long for you to be able to understand the connection between the data being generated and what you are hearing. The small investment necessary to do this will pay off on every subsequent project. If you know what to look for in the data to match up with what you are hearing, you will be able to far more efficiently produce.