Data may be boring, but it’s the best way to show how something sounds without letting you take a listen to our review units. But where to start? What is a decibel? What do any of these lines mean? We’ll be going over that today.
When you read reviews of headphones, speakers, and microphones, you often run across charts that might seem a little confusing, with very technical terms like “frequency response” or “attenuation.” These performance points are explained in the review, but if you want to read the charts yourself: a little know-how is needed. We do this because we feel like the best way for someone to find the right product for them is to have all the facts in front of them.
What are decibels?
For headphones, speakers, and other audio products, decibels (dB) are a unit of measurement that describes how powerful the sound is. Though the numbers are a measure of force, they translate pretty well into reference points for sound. For example, 0dB is just barely audible, while 100dB will really hurt your ears.
Decibels follow a logarithmic scale, which means that every ten dB you increase a signal, it is ten times more powerful—60dB is ten times more powerful than 50dB, and so on. But as far as your ears are concerned, every 10dB that your music increases will sound only twice as loud. In this case, 60dB is only twice as loud as 50dB. The opposite is also true: 50dB is half as loud as 60dB and so on.
The charts used at SoundGuys try to show how all notes are affected by your headphones using the decibel scale. We try to normalize the output so it’s easier for our readers to see exactly how much louder or quieter sounds are for each product. This helps people who know what sound they like to find the right products for them.
While we can’t simply adjust your headphones to what our review headphones sound like, we can show you what the headphones sound like in objective terms: which notes (x-axis) will come in louder (y-axis), which notes are almost muted, or if the product meet certain standards. We like to mark bass in pink, mids in green, and highs in blue so that it’s a bit easier to follow.
There’s no theoretical “best” response in every instance, so we simply describe the sound as best we can with concrete examples. For some applications like studio monitoring, there are certain targets that we’ll discuss as it’s important.
This type of chart shows how much outside noise is blocked or destroyed by active noise cancellation (y-axis), by what frequency it is (x-axis). From a chart like this, we can learn just how good or bad a set of headphones is at preventing outside noise from affecting your music.
We’ve gone over why isolation is important before, but it bears repeating: the better your headphones are at blocking out sound, the better your music will sound in noisy places. The long and short of it is: outside noise will mute certain notes of your music if it’s loud enough, so the more quiet parts of your songs, podcasts, and movie audio won’t quite make it if you can’t block outside noise.
The line above represents how well headphones attenuate outside noise. The higher the line, the better the product does at keeping your music intact in the presence of outside noise. If the line sits at 0dB, then it doesn’t block any noise at that frequency.
Microphone frequency response
Unlike a full song, our voices only occupy a certain range of notes on our charts. While their harmonics extend well into the higher notes, for most voices a range of 50-4,000Hz covers what you need to know for phone calls, voice chats, and the like. We limit the bounds of the x-axis to reflect this, just in case someone were to read too much into a swing in emphasis or muted range outside our voices’ ranges.
Just like it is in the frequency response chart for headphones, microphone frequency response charts show how well the product maintains signal at certain notes. The scale is the same for our charts, so it’s easy to tell what’s as loud or quiet as it needs to be.
For vocal microphones like you’d find in headsets, we’d ideally like to see a completely flat response on this chart, as that would mean that the microphone doesn’t change the loudness of any part of your voice. Of course, not all microphones are created equal, and some can introduce noise or compression artifacts that aren’t picked up by our testing. In that event, we’ll include clips of our voices in our reviews to demonstrate what each microphone sounds like.
Microphone polar charts
Not all microphones can be used in the same way, and because of that, manufacturers will often include what’s called a polar pattern chart to demonstrate how their microphones can be used. These “polar patterns” will often be described as “cardioid,” “supercardioid,” “bidirectional,” etc. In the chart below, imagine the microphone’s diaphragm element is right on that horizontal line, with the front facing the top of the circle, and the back facing the bottom of the circle.
The area inside the blue lines is where the microphone can record its subject, measured against the power of the sounds it picks up. The closer your subject is to the microphone, the easier it is for it to record quieter sounds.
When we investigate the data on all sorts of problems, we will often rely on charts to show what we mean. In this case, we will always tell you what each axis of these charts mean, as well as how to tell what’s good or bad. We want our content to be as easily readable as possible, so if something isn’t clear, feel free to let us know in the comments section that we need to make something a little more transparent!