Headphones and earphones come with specifications that provide basic information about headphones’ requirements and abilities. Testing a pair of headphones by using them yourself should determine whether they sound good and, most importantly, if they feel comfortable.
However, understanding headphone specifications should help you narrow down your favorite headphone. Thankfully, here at Soundphilia, we’ve put together a list of headphone specs to help you make an informed decision. You can also check out our headphone buying guide.
Impedance/Nominal Impedance
The impedance of a headphone, measured in ohms, is the amount of opposition a headphone will offer to the audio signal. The impedance of a headphone is important because it ensures you use the right source to power your headphone.
The lower the headphone impedance, the less power a pair of headphones will require to reach a higher volume. The higher the headphone impedance, the more power you need to supply your headphones to get a higher volume.
The headphone and earphone impedance range is from 8 ohms to 600 ohms or higher. A headphone with a lower impedance rating, 32 ohms and lower, is usually recommended for smartphones or portable audio players. A higher impedance headphone will require more power to sound good. This is why a headphone amplifier is recommended for higher impedance headphones.
Higher impedance headphones will not automatically translate to better sound. It simply means the headphone is suitable for a specific device or application.
Sensitivity & Sound Pressure Level (SPL)
Headphone sensitivity and sound pressure level indicate how loud the headphone will be when supplied with a certain level of power or voltage from a source. The sensitivity of headphones is measured by Sound Pressure Level per milliwatt, or dB SPL/mW, sometimes shown as dB/mW.
The sensitivity of most headphones usually sits between 80 – 125dB SPL.
A headphone with a 110 dB SPL/mW sensitivity means one mW of power will generate 110 dB SPL. The higher the sensitivity of headphones, the louder they will play compared to less sensitive headphones at the same volume setting. This means low-sensitivity headphones need more power to give out an audible sound.
Impedance and sensitivity are the two factors that determine how hard it will be to drive a set of headphones. As a basic rule of thumb, use the information below when selecting your headphones:
- 32 Ohms and 99 dB/mW – You will not need an amplifier. It can be easily driven using portable audio sources like smartphones, daps, and tablets.
- 32-80 Ohm and 99 dB/mW – Requires a high-quality PC, laptop, or smartphone. Low-quality sources will struggle to reach enjoyable listening volumes.
- 32-80 Ohm and less than 99 dB/mW – You should invest in a headphone amplifier.
- 80-300 Ohms or higher – You should invest in a competent headphone amplifier
Read more about headphone impedance and sensitivity.
Transducer Technology
The transducer technology/principle, sometimes labeled as simply ‘Type’ in other headphones, will show the design of the earcup and the type of headphone driver used.
For example, a headphone labeled ‘open, dynamic’ has an open-back earcup and uses a dynamic driver. Another headphone labeled ‘sealed dynamic’ has a closed-back earcup and uses a dynamic driver. Check out our post on open-back vs. closed-back headphones.
Besides the above examples, headphones can be labeled semi-open and other headphone driver technologies. There are different headphone drivers that include dynamic, planar magnetic, electrostatic, bone conduction, and balanced armature. The word ‘Driver’ can also be used to indicate the type of driver technology used in the headphone.
Ear Coupling
The ear coupling of a headphone is the style or design of the headphone. Headphone designs can be classified as over-ear, on-ear, and, in-ear.
Over-ear headphones are those bigger headphones with large earcups that fully cover the ears. On-ear headphones are compact and smaller than over-ear headphones. In-ear headphones are small and very portable headphones with tips that either go inside the ear canal or rest on the edge of the ear canal.
Each type of headphone design has its advantages and disadvantages, affecting how well they perform in specific environments and conditions. Your ear coupling design should work best for your preferences and listening habits
Connectivity
The connectivity of a headphone refers to the type of connection used. There are two kinds of headphone connections, which are wired and wireless. There is no best connection as each comes with its advantages and disadvantages.
Audiophiles will prefer to stick to cable connections because the sound quality will is better than wireless headphones. In contrast, consumers with busy lifestyles or those working out will choose wireless headphones.
Connector
The connector describes the type of headphone plug that the headphone features. Most headphones usually have a 3.5mm headphone plug, while others might feature the 6.3 mm phono plug or the 2.5 mm plug.
Apart from the plug, some headphones will include a plug adapter, which is usually screwed on top of the main headphone plug to allow compatibility with other devices. A common headphone plug adapter is the 3.5mm to 6.3 mm adapter.
Frequency Response
The frequency response of a pair of headphones indicates the range at which your headphone can reproduce sound.
The frequency response is the range of bass, mids, and treble. 20 Hz to 20,000 Hz is generally accepted as the standard frequency range for most headphones because of the human hearing ranges. However, some headphones offer a wider frequency range, like the Beyerdynamic DT 770 PRO, which has a frequency response range of 5 Hz – 35.000 Hz. Remember that a wider frequency response will not always mean better sound quality.
The frequency response of a headphone is measured using microphones that mimic the acoustic characteristics of the ear. When a headphone is measured, the measurements taken are what the eardrum ears.
A good headphone frequency response is flat for audiophiles with very few bumps and dips. However, others might prefer a little more bass or a little high-end. Most consumer-oriented headphones like Beats usually have a bass-heavy frequency response.
Total Harmonic Distortion (THD)
THD or Total Harmonic Distortion refers to distortion between the original signal and the audio reproduced by the headphone. Distortion in a headphone can manifest as crackling, popping, or altering musical notes, which happens when using the headphone at higher volumes.
A lower total harmonic distortion level means the headphone has a lesser chance of distorting the sound. A higher THD also means the headphone is likely to distort at lower volumes. Most reputable headphones will have THD levels below 0.1 percent, while audiophile-grade and high-end headphones have a distortion below 0.1 percent. The Sennheiser HD650 has a THD level of less than 0.05 percent.
Maximum Input Power
The maximum input power, measured in mW, is the maximum continuous power that a headphone can handle without the risk of damaging the driver.
For example, the AKG K701 has a maximum input power of 200 mW, while the Audio Technica ATH-M50x is rated at 1,600 mW. This does not mean that the AKG K701 is easier to drive; the ATH-M50x can be driven to extremely loud levels.
