Headphone Specifications Guide

by Emma Baker, Senior Editor | Published February 15th, 2024 | Reviewed by Ted Wilson, Systems Engineer

When you step into the world of headphones, you’re greeted with a barrage of technical terms and figures that might seem cryptic at first glance. But fear not, as we embark on a journey to decode these specifications and unravel the mysteries behind them. In this article, we’ll delve into how to pick out a pair of headphones, and the four key aspects of headphone specifications: Frequency Response, Headphone Impedance, Sensitivity, and Driver Size.

QC45s

Frequency Response: The Sonic Spectrum

Let’s kick things off with a term that’s integral to understanding how your headphones produce sound: Frequency Response. This spec defines the range at which your headphones can deliver audio, encompassing the high-frequency treble (around 30,000Hz) to the low-frequency bass (around 5Hz). It’s like the speaker system in your car, where different-sized speakers handle bass, mid-range, and treble sounds. In headphones, all of these elements are usually packed into a single speaker.

Headphones typically aim for a frequency response range between 5Hz to 40,000Hz, although most strive to stay within the 20Hz to 20,000Hz range. Human ears have limitations—sounds above 20,000Hz might escape our detection, while those below 18Hz might be felt rather than heard.

Some specifications use “dB” with plus/minus values, signifying how closely the headphones replicate the original recording. A lower number indicates more accurate reproduction.

High Frequencies and Clarity

When you come across headphones boasting extended high frequencies, such as above 23,000Hz, take it as a positive sign. These headphones tend to deliver clearer audio across the audible treble range. Even though few people can hear these ultrasonic frequencies, headphones with such capabilities often excel in the treble range that everyone can appreciate.

Bass and the Airtight Seal

For headphones, especially closed-back, full-size, and in-ear varieties, delivering impressive bass response hinges on achieving an airtight seal with your ears. This seal is vital for experiencing deep, impactful bass. 

However, factors like head shape, glasses, or hair can compromise this seal, resulting in diminished bass performance. The less perfect the seal, the more pronounced the bass losses.

Generally, well-designed closed headphones tend to outperform open-back counterparts in bass response. Open-back headphones don’t require a perfect seal to deliver full bass, ensuring a more consistent bass experience among different listeners. 

In-Ear Headphones: A Unique Challenge

In-ear headphones introduce complexity to the frequency response equation. The length, diameter, and shape of your ear canals affect how you perceive the frequency response. If your ear canals closely match the design target, you’ll experience the sound as intended by the engineers.

However, if your ear canals deviate significantly, the headphone’s frequency response may not align with your hearing preferences.

Custom-molded in-ear headphones might seem like a solution, but for most people, well-fitted universal in-ear headphones tend to deliver superior sound quality. Achieving a tight seal with the ear tips is critical for preserving the intended frequency response.

If your in-ear headphones struggle to block out ambient noise due to a poor seal, you’re likely missing out on their true sound quality. Experimenting with aftermarket ear tips can often help improve the seal. For in-ear headphones, regular cleaning is required to maintain a high quality sound experience. 

Headphone Impedance: The Power Factor

Now, let’s unravel the enigma of headphone impedance. This specification, represented in ohms (Ω), measures how much resistance your headphones’ circuitry offers to the flow of electrical current. In simpler terms, it tells you how hard your headphones are to drive.

Headphone impedance typically ranges from 2 ohms to over 600 ohms. The higher the ohm rating, the more power your source device needs to reach a satisfactory listening level. In the past, home stereo systems could only power 4 to 8 ohm speakers, but today, high-impedance headphones are more affordable.

Many high-impedance headphones may require a dedicated headphone amplifier for optimal performance.

The Power Play

Impedance isn’t just about volume; it’s also about power handling. Lower-impedance headphones demand less power for high audio levels, while higher-impedance headphones need more power but offer protection against overloading from headphone amplifiers. High-impedance headphones can also work with a wider range of equipment.

 

Generally, low-impedance headphones (under 50 ohms) are suitable for most consumer devices, like smartphones and computers. In contrast, high-impedance headphones shine in home setups with dedicated headphone amplifiers.

Sensitivity: Efficiency in Sound Conversion

Now, let’s explore headphone sensitivity, another crucial specification. Sensitivity measures how efficiently headphones convert electrical signals into sound waves without distortion. It’s expressed in decibels (dB), typically ranging from 85 to 105dB, and it plays a significant role in determining how loud your headphones can get.

 

Low-sensitivity headphones require more power from your source device to produce high-quality sound, but they often boast longer lifespans. 

On the other hand, high-sensitivity headphones deliver better performance with less power, but they can distort when pushed to maximum volume. It’s essential to consider sensitivity, as listening at high volumes, especially above 110dB, can harm your hearing.

The Driver Size: Small, Large, and In Between

Finally, we arrive at driver size, which plays a pivotal role in headphone performance. The driver is essentially the component responsible for converting electrical signals into audible sound. Drivers come in various sizes and types, each with its strengths and weaknesses.

Dynamic: The Common Choice

Dynamic drivers are the most common and are found in standard over-ear and on-ear headphones. They’re known for their robust sound, particularly in the low-frequency range. However, dynamic drivers may struggle with high-frequency sounds, leading to distortion.

Balanced Armature: The Tiny Titans

Balanced armature drivers are typically found in earbuds or in-ear headphones. They’re small but mighty, often used in multiples to create exceptional sound quality while maintaining a compact size.

Electrostatic: Old Meets New

Electrostatic drivers, once a hallmark of home loudspeakers, have been miniaturized for use in earbuds. They offer low distortion and relatively clear sound, making them a reliable choice.

Planar Magnetic (Orthodynamic): The Hybrid Approach

Planar magnetic drivers represent a hybrid between dynamic and electrostatic drivers. They provide a unique listening experience but are less about driver size and more about design intricacies.

In summary, while larger drivers might seem enticing for better bass, they often struggle with high frequencies. In-ear headphones with 6.5mm drivers can generate deep bass and excellent high-frequency sound. 

However, the driver’s size is just one piece of the puzzle; the overall design of the headphone and driver quality are equally critical factors that can’t always be discerned from specifications alone. The true differences often reveal themselves when you listen and experience the music firsthand.

 

Armed with this newfound knowledge, you’re better equipped to navigate the labyrinth of headphone specifications, making informed choices that align with your audio preferences and listening habits. Whether you’re craving crisp trebles, earth-shaking bass, or an all-around balanced sound, these specifications will guide you toward your ideal pair of headphones.