Earphone Specifications Explained

Many people buy some sort of portable hearing device. By this I am referring to earbuds (like the iPods have bundled), in-ear earphones (like Apple’s In-Ear), over-the-ear headphones (like Sennheiser’s PX series) or large cans (something like the Sennheiser HD series). For the sake of simplicity, I’ll just refer to these as “earpieces.”

When you’re buying a new one, whether  you’ve lost your iPod earbuds or you’ve frayed your last pair, you will almost always see, technical specifications.  Most of you will gloss over these, ignore them, or — at best — glance at them and shrug your shoulders because few people really know what all those numbers mean.  I’m here today to help explain all of those seemingly random figures, and hopefully help you along the next time you set out to buy a new earpiece.


The first concept to understand when looking and scanning through these specifications (or any other set of technical specifications, for that matter) is that not all of these specifications are worth noting. Not all of the specifications will affect the average user’s listening experience.   Some, in fact, are not humanly possible to detect.

To start, there are really only three specifications which are likely to affect your overall listening experience:

  • Driver Type
  • Impedance
  • Noise isolation

In-Ear Monitors

First off, what is a driver? In everyday English, it’s just a mini-speaker. It’s the part of your In-ear/earbud/headphone that is a miniature speaker.  In most earpieces, there are really two main types of drivers; dynamic drivers, and balanced armature drivers.

Dynamic drivers are…. well, dynamic. They change with age. Just as fine wines grow better as they age, so do these drivers. Out-of-the-box sound will appear harsh, and lacking refinement. Hence, these dynamic types require what is known as “burn-in.” This just means that they are not at 100% sonic performance when they are taken out of the box, and need to be used before they can improve and finally reach their peak 100%. Usually the manufacturer will give a recommended amount of “burn-in,” in terms of hours. This, in turn, also widely varies according to the way each driver is designed. While some only need about 50 or so hours before reaching its potential, some, like my very own pair of Sennheiser IE8s, need 500.

Armature drivers, on the other hand, are more stable. Out of the box, they are much nearer to their peak state. While they still do improve over time, the improvements are subtle.  Therefore, many users view armature drivers as the better option because you can enjoy them at almost peak capacity instantly.

If you base your decision solely on the lack of burn in time, however, then you really risk making a premature judgement.   Generally, dynamic drivers have a much wider frequency response. An example of a single dynamic driver’s range is from 10-20,000Hz, while a single balanced armature driver may get 40-16,000Hz. In order to circumvent this problem, however, you will find that several manufacturers put several balanced armature drivers together in a single earphone. Examples are the Westone UM2 (dual-driver) and the Westone 3 (triple-driver). By assigning high frequencies to a driver, mids to another, and low frequencies to another driver, they cleverly uses the armature design and overcomes the frequency response shortcomings.

But that is not all, before you make a decision, you will also want to look at the impedance specification. The higher impedance a piece has, the harder it is to power. Say you plug in the standard iPod earbuds (32 ohms impedance) into an iPod and put the volume about halfway. This volume is perfectly acceptable on the earbuds. However, if you plug in a large headphone, with impedance figures of say, 300 ohms, the volume becomes is reduced significantly. Hence, headphones with such large numbers may require a portable amplifier in order to properly power them, and this should be a consideration. Generally, as a safe limit, anything up to 32 ohms is just about drive-able by portable players.

Finally, there is noise isolation. This specification is pretty much self-explanatory. High-end in-ear phones generally plug your ears in order to block outside noise, generating up to 26dB of isolation. The higher the sound isolation specification, the more outside sound gets cut. This should not be confused with noise canceling headphones, which emit a tone to create a sound barrier.  While both methods do block outside noises and sounds, noise isolation is a much cleaner solution, and does not risk distortion of the music like noise cancellation can.

In reality, there are many more specifications usually posted by earphone manufacturers, but these are of very little, if any, consequence. Some of these other specifications you may see are include “driver size,” “frequency response,” “sensitivity” and “max power input.”  The truth is though, if you pay attention to the areas discussed above, then I think you will end up with an exceptional listening experience.

Images courtesy of head-fi.org

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Gear Diary Staff
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2 Comments on "Earphone Specifications Explained"

  1. Ryan Phillips | May 2, 2009 at 5:57 pm |

    iPod… Audio-File: Earphone specifications explained | Gear Diary: When you’re buying a new one, whe.. http://tinyurl.com/dykcfq

  2. Thank you for this!!!

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