What is EQ and why is it important in improving sound?

I still remember that moment vividly: sitting in the car, turning on Van Halen’s 5150 and spending the entire album tinkering with the 10-band equalizer I had installed to get the best sound possible.

You don’t see many physical equalizers these days, which is a shame because they were always nice to have. Instead, most things are now controlled by software. And that’s okay. It may not be “audiophile-grade good” but at least it’s something.

For those of you who didn’t spend your youth trying to adjust every knob and button on your audio rack to get the best possible sound from your speakers, you might be wondering, “What is this EQ he’s talking about?”

Let me explain.

What is the frequency…

One way to measure sound is by periodic oscillations, which are hertz (or Hz), is the characteristic of sound that determines pitch. Humans have a finite range of frequencies that they can hear, namely 20 to 20,000 Hz. Those frequencies are divided into octaves:

• 16 – 32 Hz – is the lowest frequency that humans can hear.
• 32 – 512 – rhythmic frequencies (low and high notes)
• 512 – 2,048 – range where human voice is located
• 2.048 – 8.192 – range over which labial and fricative sounds are produced
• 8,192 – 16,384 – brightness, bell, cymbal and screech range
• 16,384 – 32,786 – vague sounds beyond the range of human hearing

How do you put that into more understandable terms? To break frequency down into its simplest terms, you have:

• Low score – first two items on the list above
• Mids – the third and fourth items in the above list
• High score – last three items on the list above

Equalizers allow you to boost or cut specific frequencies, and different EQs offer different levels of adjustment. For example, you can buy some cheaper earbuds that come with an app that offers custom EQ options, but the EQ is limited to three bands. Typically, a three-band EQ allows for adjustments to the bass, mids, and treble. The problem with a three-band EQ is that you don’t get any precise control. In other words, if you boost the “bass” in a three-band EQ, you’re boosting everything from 16 – 512 Hz. What’s the problem with that? Let’s say you want more kick drum in your mix. If you boost the bass in a three-band EQ, you’re not only boosting the lowest frequencies, but also the upper bass, which can make the sound a little muddy.

Boost your three-band EQ to a five-band EQ and you’ll have a little more control. A typical five-band EQ might give you the ability to boost specific frequencies, like 60 Hz, 230 Hz, 910 Hz, 3,600 Hz, and 14,000 Hz. Now you can boost 60 Hz and get a little more kick drum punch in your mix. At the same time, you can lower 910 Hz to lose a little of that thinness (too much midrange and it becomes very thin).

A ten band EQ can be divided into:

• 31.25Hz
• 62.5Hz
• 125Hz
• 250Hz
• 500Hz
• 1kHz
• 2kHz
• 4kHz
• 8kHz
• 16kHz

Note: kHz is kiloherz

Now we are talking.

I used a 32 band equalizer and you can imagine how much time I spent tweaking it. In larger EQs, the sound is usually divided into low, low/mid, high/mid, and high. Each EQ is different but they all do the same thing… boost or cut specific frequencies to change the overall sound of the device.

Why use EQ?

Let’s say you just bought a pair of earbuds, and when you open the box, they sound cheap. Typically, cheap earbuds and headphones have a similar sound palette — tinny bass, over-the-top mids, and dull highs. You’ve heard them before; everyone has.

That’s where EQ can come in handy. Many Bluetooth headphones recommend downloading and installing a companion app, which often includes an EQ. Install the app, connect your headphones, and make the following adjustments:

• Increase low level
• Midrange reduction
• Increase the high level

Create a nice sloping curve down to the mids and a rising curve to the highs. Now play your favorite song and see how those cheap headphones sound. Big improvement, right?

You’ll also find that the app has a number of presets to choose from, often grouped by genre. As you might expect, different genres of music are improved by tweaking certain frequencies. For example, if metal is your thing, you’ll want to boost the bass and treble, but be careful about boosting the mids/lows, or the sound will sound muddy. If you listen to a lot of podcasts, you’ll want to boost the mids, as human voices are central. Classical music tends to benefit from a fairly flat EQ when listening through headphones or earbuds, but can really come alive with some added bass and treble when listening through speakers.

EQ is a personal matter

The thing about EQ is that it’s so personal. You can talk to 100 audiophiles or audiophiles and hear 100 different opinions. What’s most important to you is finding the EQ curve that best suits your needs. And since everyone’s hearing is a little different (for example, I’ve lost about 50% of my hearing in my right ear, so I have trouble hearing high notes unless they’re hit a little harder than normal), I know exactly how to set my EQ to my exact taste.

It’s not just about your hearing. You also have to consider your equipment, the room you’re listening in, the ambient noise, etc. All of those things affect how you adjust the equalization to get the most out of what you’re listening to. And if you have a subwoofer attached, you’re talking about another layer of consideration (do you let the crossover just send the lowest frequencies to the subwoofer, or do you give it a little more?).

After using EQ long enough, you’ll get the hang of it and be able to quickly tweak EQ sliders (whether physical or digital) to get the best possible sound.

Any opportunity I can get to improve the sound I hear, I’ll take. If that means using EQ, I’ll do it… and have fun doing it. The only word of warning I want to give you is that EQ is a deep rabbit hole to dive into. At the same time, it’s a very rewarding chase to perfection.