What is Uniformity in Speaker Response

When calibrating your speakers, most people rely on their room correction programs. Fair enough. Most of us don’t have the equipment, knowledge, or time to do it manually. But one term that is thrown around is getting your speaker’s response more uniform. What does it mean to have more uniformity in your speaker’s response? And how does it help you and your room correction program make your system sound better? Let’s break it down.

Uniform is Not the Same As Flat

Many people conflate a uniform speaker response with a flat frequency response. When we talk about speakers, we are often looking for a flat response. As a reminder, a flat response is measured in a lab (usually an anechoic chamber) ensuring that the speaker recreates every note at the volume requested by the amplifier. As you may be aware, your room is not an anechoic chamber.

A speaker being measured in an anechoic chamber. The walls are covered in very large sound absorbers.

Once you put a speaker in a room, the room affects how the sound waves interact. That’s why anechoic chambers are covered in very large absorbers. They absorb any reflections so that what is measured is the speaker’s response alone. In your room, the measured response will be far different from what they would measure in a lab.

So What Is a Uniformity in a Speaker Response?

When we talk about uniformity we are always talking about multiple measurements of a speaker’s response. If you’ve run a room correction program recently, you’ve probably had it ask you to place the microphone in multiple “seats.” This isn’t exactly correct (check out our article on proper microphone placement), the key is that the room correction is trying to get an idea of how the room is affecting your speaker’s response. The easiest way to think of it is to imagine putting all of those measurements on the same graph. For example:

Yes, I know these are stock images. Just go with it.

Say you took two measurements and put them on the same graph and they looked like the image above. As you can see, while the amplitude is greater for one line than the other, they both vary in the same direction. Both lines go up at the same frequencies, and both lines go down at the same frequencies. They don’t go up or down by the same amount, but they are in the same direction. We’d say that these two speaker response measurements are fairly uniform. Now, let’s add a third:

With this third, yellow line, the peaks and dips do not line up with the blue lines. This measurement is not as uniform a response. At either end, it looks okay (they start to line up again). But not in the middle.

Why is Uniformity Important?

It all comes down to your room correction. Your room correction is looking for what it can do to make your response more even (and flat) for every seat. It does this by adding EQ to the signal sent to your speaker. This adjusts the volume of the sound at specific frequencies. So, for the first graph, it can add volume to correct the dips and reduce volume for the peaks to give you a more straight line at every seat.

But the second graph…that’s problematic. It can EQ both ends because of the uniformity of your speaker response, but not at the middle. Anything it does in the middle will make something worse at one or more seats. Take the dead center of the image. If you cut the volume at those frequencies, the yellow line will go down, but the blue lines will go WAY down. That’s not great for the blue seats. If you boost the volume, the blue lines will go up (and those seats will have a more even experience), but the yellow line will go WAY up.

So, what does the room correction program do for those frequencies in the center? Nothing. Because anything it does will make some seats way worse.

Take Away

Uniformity in your speaker’s response is important so that your room correction can adjust the speaker for a more even experience at every seat. Your speaker may be perfect in the lab, but your room will make a big difference in how it sounds in your home. That’s why it is so important to do everything you can to your room first so that you can get the best results.

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