When you go online to shop for earbuds or in-ear headphones, you see a lot of specs like driver size, impedance and sensitivity. Do these specs point to better sound quality? Should you choose in-ear headphones based on their specifications?
Let’s have a look at some in-ear headphone specs and how they actually change the sound quality.
Type of Driver: Dynamic vs Balanced Armature
Dynamic drivers need air to produce sound, and the more air they can push, the more bass they can reproduce. It works the same way you need air to breath. Without air, dynamic drivers are dead and they are not able to produce any sound through earbuds. The sound is produced when the diaphragm within the driver vibrates by a coil, which is why it is also known as a “moving coil driver”. Dynamic drivers are able to generate a wide range of frequencies which encompass the entire musical frequency range (1Hz to 20,000 kHz). The higher the frequency, the better.
Dynamic earbuds are constructed by 3 main components: permanent magnets, voice coils, and diaphragms.
Dynamic drivers produce sound when the air that fills the space between the coil and the diaphragm vibrates. There is a vent, located strategically on either the driver housing or the diaphragm, that lets air in and out. The position of the vent as well as the size and diameter of the diaphragm are what determine how much bass is produced.
The dynamic driver manages to tune sound by conveying electrical signals from the source (for example a smartphone or tablet) to the voice coil, which then causes the diaphragm to vibrate. The whole structure of the dynamic driver is designed in a way that enables the diaphragm to vibrate as strongly as possible, in order to generate greater air pressure.
This is the reason why dynamic drivers produce the most powerful bass, with a warmer sound than other types of drivers. Most of the in-ear headphones being sold today use the dynamic driver mechanism because mass production is not complicated or costly making these earbuds quite affordable.
If you want better sound with more rumbling bass, go for in-ear headphones with larger housing, as larger dynamic drivers perform better because they can push air stronger. If you look at the market you will see some Sony in-ear headphones such as Sony MDR-XB90EX labeled “extra bass”. These have larger drivers that are able to handle the low-end sounds better. See our full review of the XB90EX here.
Balanced Armature Drivers
Unlike dynamic drivers, Balanced armature drivers (BA) do not need to make air vibrate in order to produce sound. Since they do not require air their performance is not dependent on their size, and can be designed much smaller than the dynamic driver. In terms of sensitivity, BA drivers give a more stable, accurate, and clear sound. Though the BA drivers are lighter than dynamic drivers, they do not deliver low frequency sounds and therefore the bass sound goes missing at some levels.
Audio manufacturers managed to provide a solution for this problem by equipping in-ear headphones with more BA drivers. Each pair of drivers is designed to take care of a different level of frequency (lows, mids, and highs). However, these types of in-ear headphones are extremely pricey. For example, the JH Audio JH16Pro contains 8 BA drivers and costs a whopping $1000. There is also an extra fee that you will be charged when you go to one of their audiologist to get custom eartips fitted.
The intensity level Balanced armature vs. Regular
For those who want it all, look no further than Sony’s XBAH3 which are designed with two dynamic drivers and one balanced armature driver, which solves all the problems connected with the shortcomings of both types of drivers.
On every packet of in-ear headphones you purchase, you will see numbers such as 20Hz – 27,000 kHz. What do these numbers mean? The 20 Hz refers to how low the frequency of the in ear headphones can go when generating bass response, while the 27,000 Hz refers to how high the frequency can go when generating the treble.
The higher the frequency, the higher the capacity the in-ear headphones can handle for treble. The lower the frequency, the lower the capacity the headphones can handle for bass. Though some in-ear headphones offer frequencies as high as 33 kHz and as low as 1 Hz, this translates to higher clarity, but not always better sound quality. In instances where the frequency goes below 20 kHz, you will feel and hear the bass more than the actual music. You can hear well up to around 20 kHz, but anything more than this is just hissing sound. That is why we cannot judge in ear headphones based on their frequency capacity alone.
Impedance is measured in Ohms (Ω), and is classified as either high or low. If the impedance of headphones is greater than 100 Ohms, we consider it to be high and therefore able to be used with high-power output devices like amplifiers. However, there are no such in-ear headphones being sold today. Headphones can have high impedance because they are protected from overloading. High impedance eliminates the hissing sound created by electricity when it conveys vibrations of frequency emitting sounds.
When the coils are wound with many layers of thin wire the dreaded hissing sound is eliminated because there is no room for air between the coils. High impedance also results in clearer sounds, and devices with this kind of range have adequate protection to enable them be used with various devices.
The impedance of headphones tends to be low, meaning that you cannot plug them into a device that generates a high power output such as home audio devices – the earphone transducers will simply explode. The majority of the in-ear headphones being sold right now have an average impedance of 12 – 36 Ohms, which enables them to work with portable devices. The actual impedance varies depending on the frequency of the source.
Sensitivity is measured in terms of decibels (db) and sound pressure levels (SPL). A decibel is a measure of how loud a sound is. It is calculated as follows:
db = Log (sound level/reference level)
For example, if the sound level is equal to the reference level, then the db will be equal to zero. This is as close to complete silence as you can get while still producing enough sound to hear something. It is also possible for the db to give negative values, for example -1. This occurs when the sound level is less than the reference level by a factor of 10. It is not advisable to go higher than 85db’s for a prolonged period of time because the sound can cause permanent hearing loss.