There is always that one feature that separates ‘good’ from ‘better’; and ‘better’ from ‘best.’ Some features make all the difference between products by a particular brand and also between products that perform the same function.
Just because you’re looking for a particular feature doesn’t mean you shouldn’t take into account other components. This does not mean that the basics should be neglected just because one is looking for that distinguishing feature.
For example, if you were to buy a pair of running shoes, your first thought would not be the color or how fanciful the shoes look. You would look for essential features like the design of the sole, as this determines how much traction it will get on the road while you run. This is also the same thing, if not more intense, when looking for certain products like Headphones. This is important because the basic characteristics of headphones are what help a buyer determine what product he decides to buy.
This article seeks to bring to fore some technical characteristics of headphones so that you can make an informed decision. These characteristics are listed in order of importance, and they are:
1. Headphone Drivers
This is very important, if not one of the most important aspects when choosing a headphone. The driver of a headphone is the element that transmits electrical/audio signals and converts them into audible sound waves that are heard by the listener. Drivers usually consist of magnets, a conductive wire/coil, and a membrane/diaphragm.
Electrical signals make the membrane vibrate, and these vibrations cause sound waves that are audible to the listener. Manufacturers usually indicate the diameter of the drivers used in producing the headphones, and this is usually measured in millimeters. It is generally believed that the larger the diameter of the driver, the better the quality of sound produced. This is especially important for bass sounds.
The diameter of the driver is also crucial with regard to the type of headphone. For example, if it is an over-the-ear headphone, it is believed that a driver with a minimum of 40mm is the best bet, while for in-ear headphones, an approach called ‘dual-driver’ is used (what this simply means is that more than one driver is used, usually 2; one for middle and high sound waves while the other driver is used for bass and low sound waves).
Also, the type of connector used is as important as the drivers used. Manufacturers use materials like Stainless Steel, Gold, Chrome, and Bronze more frequently. The type of material used determines the quality of electrical conduction that occurs.
2. Sensitivity/Sound Pressure
Ideally, headphones are manufactured with good Sensitivity to sound. This is what the term ‘Sensitivity’ means; the ability of the headphones to detect sound even at the tiniest change/volume. This term is used interchangeably by manufacturers with Sound Pressure. They are used to indicate how loud the headphones can go. Sound Pressure Levels are used to measure the Sensitivity of headphones, usually indicated as decibels per milliwatt (dB/mW). In contrast, Sensitivity shows how efficiently an electric signal is converted into a sound wave.
To understand this concept better with respect to the different levels of sound, I will give examples. Regular vehicular traffic is around 81Db, a shout or loud voice is around 107dB, whereas an airplane taking off is about 132dB. Most headphones are manufactured within the range of 85-120dB/mW of Sound Pressure Level. The Occupational Safety and Health Administration postulates that the threshold of pain for sounds is at about 120dB, and so listeners are usually warned about the dangers of prolonged exposure to sounds higher than 85dB as it can lead to hearing loss and cancer of the auditory canal.
The Sensitivity of headphones is important because it helps you understand how to regulate volume and how the volume affects the Voltage. Sensitivity expressed in decibels per Voltage (dB/V) relates directly to the frequency. For example, changing the volume by 6dB requires a voltage increase up to two times. Also, Sensitivity affects volume with regards to resistance. Higher Sensitivity and low resistance give a higher volume, even though this means that there might be extra noise (perhaps from the amplifier, etc.). The extra noise will only be heard when there is no music playing, so it might be noticed. Still, it is generally believed that headphones with higher Sensitivity will be louder.
3. Impedance (Electrical Resistance)
Most headphones work using electromagnetism. Therefore, it is important to understand how electrical resistance (or Impedance) affects the sound quality and the type of headphones you are about to purchase. Impedance is measured in Ohms and affects the power of headphones in that the higher the resistance, the higher the power used to drive the headphones. High-end and top-quality headphones have a higher impedance (of at least 300 Ohms) and require an amplifier to power them. On the other hand, headphones used for mobile devices have a relatively lower impedance (of 40 Ohms and below) and require less power. This might look like an advantage, but lower impedance headphones require a higher current, which creates vibrations that further create sounds. This is why one might hear an audible background hiss/cackle when using lower impedance headphones. This phenomenon can lead to performance issues, which is why Impedance is very important as a mismatch can frustrate your experience.
4. Frequency Response
Frequency response is a term used to indicate the range of sound frequencies that the headphones can produce. Frequency Response is usually measured in Hertz (Hz) with the highest number representing the frequency that produces treble notes (usually indicated as ‘Light’) and the lowest number indicating the amount of bass produced (usually indicated as ‘Dark’). Most headphones have a stated frequency that matches the frequency of human hearing, usually between 20-20,000Hz.
This range does not really translate to good sound quality, but Frequency Response is important in that it helps you choose the right kind of headphones you need for a particular music type. So, if you want to listen to music that has lots of basses, then choose a headphone that supports the bass frequency. Something important to note about the Frequency Response of a headphone is that at the highest frequency, the Frequency Response is always wavy, and so the notes produced by the headphones might sound a little sharp at those frequencies. But most headphones do not have a wide difference between high and low frequencies.
5. Total Harmonic Distribution (THD) and Noise
This characteristic is sometimes split between THD and Noise. Noise characteristics are usually Noise Isolation and/or Noise Cancellation. While THD refers to the amount of distortion, the noise factors refer to the amount of noise the headphones can accommodate or prevent. THD shows the distortion of sound, usually when using the headphones at a high volume. Headphones usually produce sound through the vibrations of the diaphragm in the driver; however, at high volumes, the diaphragm may not be able to vibrate fast enough, leading to distortion in the sound. THD is often expressed as a percentage. The lower the THD, the better the quality of the headphones. Most headphones have a THD of 1% or even less with high-end products.
- Noise Isolation refers to the ability of the headphones to block out external sounds. This ability is seen in over-ear, closed-back, and in-ear headphones because they usually seal the ear canal while in use. This is why it is important to get the correct size of ear tips when using in-ear headphones. Noise isolation is not limited to frequencies and does not require and external power supply. It is passive and appears in more affordable products.
- Noise Cancellation, on the other hand, is a little more technical than Noise Isolation. Noise cancelation is the ability of the headphone to trap sound, create an inverse wave, and feed it back into the headphones with embedded microphones and electronic chips. This feedback is what effectively cancels out the sound. Noise cancellation is very effective for low frequencies, less effective for mid-range frequencies, and not as effective for higher frequencies. This means that you might still hear high-frequency sounds while your headphones tune out low-frequency sounds. It is necessary to mention that noise cancellation often requires battery power, and its overall effectiveness varies.
Most of these technical characteristics are indicated on the box of the products. Manufacturers have their individual measuring standards though, even though these standards usually mean the same thing, and yet bear different units. And if the characteristics above sound too technical for you, just remember that when buying headphones, you should be interested in the width of the driver (the headphone’s main element), the quality of the sound it can produce with regards to notes (how much bass it can produce and vice versa), how much power it will need to function and how well the headphones can block out sound.
When you know all this information, you can then go ahead and shop for that headphone like a professional because you basically know the technicalities of the product.
And the last note to boost your confidence? No one will call you an amateur when you share these tips with a friend who is also looking to buy a new pair of headphones!