Why measure when we have ears?
A few reasons to start with:
While having a working pair of ears is vital, our ears are not trustworthy when it comes to analyzing phase and time offsets and provide no way to store and recall aural information.
Our ears are not scientific tools.
Our sensitivity to frequencies is not based on a flat line but a curve that is based on SPL
Our ears get tired, especially if subjected to high SPL
Our hearing is affected by air pressure and temperature
We lose our hearing as we age
Our hearing can be affected when we are sick
Traveling by plane can affect our hearing (not for the better)
There is no “standard” for good and bad hearing.
Hearing is subjective.
Don’t we have ears to measure audio?
I would suggest we have ears to hear but not to “measure”. To measure something implies a reference point.
Why do we use a tape measure when we could guess how long a wooden board is? Because our eyes aren’t good at judging distance. Simple.
Considering the non linear nature of the human hearing mechanism, I would suggest that our ears are absolutely important but not as scientific measurement tool.
Take a look at this chart:
Let’s look at an ear / eye analogy. If I was going to measure the color (frequency) of something my eyes would be a lousy measurement tool. Our eyes are constantly adjusting for brightness and color.
WIKI – Adaptation (eye)
WIKI – Purkinje Effects
“The human eye can function from very dark to very bright levels of light; its sensing capabilities reach across nine orders of magnitude. This means that the brightest and the darkest light signal that the eye can sense are a factor of roughly 1,000,000,000 apart. However, in any given moment of time, the eye can only sense a contrast ratio of one thousand. What enables the wider reach is that the eye adapts its definition of what is black.
The eye takes approximately 20–30 minutes to fully adapt from bright sunlight to complete darkness and become ten thousand to one million times more sensitive than at full daylight. In this process, the eye’s perception of color changes as well (this is called the Purkinje effect). However, it takes approximately five minutes for the eye to adapt to bright sunlight from darkness. This is due to cones obtaining more sensitivity when first entering the dark for the first five minutes but the rods take over after five or more minutes.”
If I wanted to measure colors, I would use a color analyzer so I could reproduce that same color. Think of the paint kiosk at a large home improvement store. You take them a sample and they can match it. Picture what the result would be if the person working at the paint counter tried to eyeball the new color. “A little bit of green, a smidge of red, etc…” Needless to say you wouldn’t be pleased with the color match once the new paint went on the wall.
Like our sight, our hearing is also susceptible to change. Fortunately with an audio measurement rig, you can rely on your ears and your eyes and your measurement rig results to come to a conclusion. Is the system flat? Flat compared to what?
A working pair of ears, a working pair of eyes and a working measurement rig are a superior toolkit compared with just a pair of ears. It’s 2014 folks! The era of working without the proper tools should have ended back in the 80s when Meyer SIM 1 & 2 came out but certainly in the 90s when SMAART came out and revolutionized the audio industry. Many in our industry are still working in the proverbial stone age when it comes to optimizing sound systems.
Having been an audio engineer for more than 25 years who didn’t own a measure rig until the last 5 years and realizing that I really didn’t get serious until about 2 years ago, I can honestly state that I wish I had been measuring the whole time. I’ve achieved results by measuring my sound systems that I would of never achieved using just my ears.
Even the best speakers money can buy are a compromise and their performance is based on local conditions. Put those speakers in any acoustic environment and now there will be tuning work to be done if you want a linear system. Since there is only so much time that can be allotted for “tuning” a sound system, having a measurement rig makes the process quick and painless and allows for storing of the information so you can use it in the future. The biggest advance I’ve made using a measurement rig is that I can verify what I hear with my ears which gives me confidence in the decisions I make.
Having a measurement rig and acquiring the skills necessary to use it will literally save time, money and further your reputation.
In a recent conversation with a prominent measurement engineer it became obvious that all things being equal (same PA, same amps, same processing, same venue) the determining factor on how that sound system will sound is completely up to the measurement engineer. You may get an account just because your PA sounds better than the next guys. Even if the PA’s are the same. I think measuring is that important. It is the determining factor to your success.
If you provide sound systems for others, are responsible for maintaining a permanently installed sound system, work in a shop that rents audio gear, have a mic collection, etc…I would strongly suggest that you build a measurement rig and gather at least a basic understanding of how to use it. The tools (hardware and software) are affordable and the principles are well documented now.
Mics get damaged
sound systems get wired incorrectly
audio components degrade over time.
With a measurement rig, you have the ability to verify proper function of everything in your audio system. If you make reference measurements when a mic / DI / speaker / audio device is brand new and maintain a library, you’ll know exactly what to expect when you measure these items later.
I encourage you to assemble a measurement rig if you don’t have one already and commit to learning how to use it. Learn how to understand what to do with the results if you haven’t already. DO IT!