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The Blind Reference EQ Technique

Buried inside the art of audio production is equalization

Sometimes the pain involved in the subjectivity of audio production results in hours upon hours of nerve-racking experimentation. From pairing up microphones with the right processor to the final mastering process on a DAW, all sorts of tinkering and doctoring takes place.

Buried inside the art of audio production is equalization. And then buried in equalization is the long-running debate between �subtractive� and �additive� equalization. Engineers have been arguing for decades about when-or-when-not-to-add-or-take-away-what-frequencies. With that in mind, I propose another option. It may not be original, but for the sake of this article, let�s say it is and call it the �Blind Reference EQ Technique.�

I found recently that a voice-over track was incessantly muddy in the lower-mid range of frequencies. What frequency or combination of frequencies needed to be added or subtracted to add clarity to the track? Do I use a graphic or parametric equalizer? Or do I get mad and cry?

I decided that I wanted to pinpoint the frequencies and do a detailed (and very manual) sweep of the voice track. Using the DAW, I put the track in loop mode and opened up a 30-band equalizer. The EQ was perfectly flat, and I grabbed the 63 Hz �knob� with the mouse and then�closed my eyes.

We don�t mix sound with our eyes. Sure, the eyes are useful for watching meters and what-not, but we definitely don�t hear with our eyes. With my eyes closed, I ramped 63Hz all the way up and slowly brought it back down to where I thought it sounded right. Luckily, when I opened my eyes, it was flat again. Whew. My ears aren�t crazy yet!

I continued this process through the 100 Hz range and into 250 Hz. I knew, based on past experience, that as I neared 300 Hz (or so) I would probably subtract that frequency considerably.

With eyes closed, I cranked up 315 Hz and began pulling it down. When it sounded right, I opened my eyes and saw that I had only taken it down to -2 dB! What? Normally I pull it down more than that!

The real learning experience came when I moved along and reached 500 Hz. Using the same �boost and sweep� technique, I began subtracting 500Hz and didn�t stop until it was at -10 dB!

Concerning the voice track used for this experiment, which happened to be my voice, I had never considered reducing 500 Hz that much. Why? Because my eyes had become key influencers concerning how I should handle 300 Hz on voice tracks. It�s almost as if I could hear too much 300 Hz on the voice track if I didn�t see it notched out on the equalizer.

Yes, standard procedures should be appreciated during any subjective type of work, but they should not become rock-solid rules. �By running my comfortable EQ settings through the �blind reference� test, I found that I was actually tinkering with the wrong frequency all along.


The biggest problem during critical listening is the phenomenon known as �ear fatigue.�

The ears basically become numb to the finer parts of crafting audio. Soon, the engineer can�t hear the nuances of compression, equalization is hard to pin down and in severe cases, differences in pitch become imperceptible.

When the ear is fatigued, it�s time to stop.

1.����I usually try to spend less than 15 minutes in �tweak mode.� After 15 minutes, I feel like I need a reset, so I go get a snack and come back later.

2.����Unless it�s absolutely necessary, never tweak using headphones. A good set of near-field reference monitors create a healthier listening environment.

3.����I also shamelessly �A/B� against the best. If you know of a recording that was engineered properly, see how your equalization matches up against theirs.

One more note: Blind referencing may actually be easier with a graphic EQ and nearly impossible with a parametric EQ. I say this because parametric equalizers have parameters for bandwidth. Put simply, unless you know your equipment or DAW really, really well, you can�t adjust that many parameters with your eyes closed! Graphic EQs let you hone in on one frequency at a time. When you�re finished blind referencing, you�ll see an EQ curve that accurately demonstrates the equalization correction per your ear and not what your eyes thought you should hear. Good luck!