What is Headphone Sensitivity?
You are in a search for your perfect pair of headphones but you’re not sure where to start.
In order to make a smart choice, it’s best if you can learn how headphones work in the first place. Why? Because by learning how headphones work and what kind of designs exist, you can narrow your choice and choose exactly what you need.
Understanding the headphone specifications
Buying headphones can easily turn an exciting experience into a quite confusing experience, especially if you don’t understand any of those specifications that many of the manufacturers list on their web pages. Maybe for many of you words like drivers size, impedance, total harmonic distortion (THD), or headphone sensitivity seems quite familiar, but for those of you that don’t quite understand the meaning of those words, we are going to explain them for you.
1. Driver size – The most important unit of an earphone is the driver which converts electrical signals into sound. If you want to understand it even more, think of it as a small loudspeaker inside your ear that creates the waves that allow you to hear the things. Earphone drivers are disc-shaped and are composed out of three components:
• A magnet,
• Voice coils
• A diaphragm.
Drivers can range in size for example a small driver can be from 6/12 mm or bigger drivers in size of even 106 mm.
You can see many manufacturers bragging about their offer of drivers bigger than 100 mm, but what does that mean for you? What is the advantage of having bigger drivers?
Experts claim that headphones with bigger driver size give more bass.
That doesn’t mean though that they are louder or more powerful, because the size of the drivers isn’t a relevant metric that from which you can choose what kind of earphones are the best option for you.
2. Impedance – This metric explains how much your headphones resist electricity. Sounds confusing? It doesn’t need to be. Impedance is measured in 0hms. The lower the 0hms is, the less power you’re going to need to drive the headphones, the higher it is, the more power the headphone will need. Think of it this way. The number of 0hms you need explains if you can use your headphones, let’s say with your mobile phone.
For example, if the number of 0hms is between 1 and 32 0hms, that means that your headphones can be driven by your smartphone and you’ll get a good volume. If the number of 0hms goes to 100 then it’s quite difficult to drive your headphones with your smartphone, and if the number of 0hms goes to 250 then it’s going to be impossible to drive your headphones without an amplifier.
So although having headphones with high impedance means that your headphones express the sound in a better way, if you are the type of person that usually uses the headphones with your smartphone, then you need low impedance headphones.
3. Total harmonic distortion (THD) – Very important specification when choosing the right headphones you need because it measures how much the audio signal changes from the time the signal enters the headphones to the time the audio signal enters your ear. Most of the manufactures these days offer headphones with very low distortion. When looking at the manufacturing specifications, choosing headphones with a THD lower than a 1% on a 100dB means you’ve chosen yourself a good pair of headphones.
What is headphone sensitivity?
Simply explained, sensitivity in headphones explains how effectively headphones convert an electrical signal into an acoustical signal, or in other words, sensitivity in headphones explains how loud the headphones will sound when a specific voltage is applied to them. When speaking about the sensitivity of headphones we also mention the SPL or the Sound Pressure Level because of its importance in measuring the level of sound we humans can hear.
Sensitivity in headphones is measured at sound pressure level the headphone can take per watt - dB/mW, per milliwatt – dB/mW or millivolt – dB/mV of power. Although most of the headphones have sensitivity range from 80dB/mW to 120dB/mW, the safe range of sensitivity for our ears goes from 75dB/mw to 110dB/mW.
Low sensitivity vs High sensitivity
There are two factors that explain the sensitivity of the headphones: the impedance which explains the amount of power you’re going to need to drive your headphones, and the efficiency which explains the energy transfer.
Higher sensitivity headphones offer better headphone performance without using a lot of power, but in this case there is also a chance of appearance of distortion if using a very high volume.
Lower sensitivity headphones require a lot more of power, but are also more durable than higher sensitivity headphones.
When we speak for headphones with higher sensitivity, usually we mean better driver performance without using much power. But, what we must be aware of is that if we use headphones with high sensitivity on high volume we can cause damage to the headphone’s drivers but also to our ears. Although this is not the case with the low sensitivity headphones, their down side is that you’re going to need a high power supplying device like a headphone amplifier to get better sound reproduction.
When in search for your ideal headphones, sensitivity is not a good metric in determining whether the headphones you’re going to buy are good or not. Sensitivity can only show you if the headphones you’re planning to buy will play as loud as some another pair of headphones if you set them on the same volume level.
If you use a system that has with a low output level and match it with low sensitivity headphones it will give the result of a low SPL. If you choose to increase the amplifier for the same combination it will lead to distorted audio sound.
On the other hand, if you choose to use high sensitivity headphones and match them with a high power amplifier, you’re going to need to use a low volume setting which can then result in hearing bigger noise.
If you tried to connect your headphones to an airplane sound system while flying then you’ve already experienced this kind of a problem. If you tried to set the volume on the first position, you probably got enough volume level but you can also hear the noise, and if you tried to increase the volume even a bit more, then it gets too loud to use.
Why Headphone Impedance and Sensitivity are Important?
When speaking about buying the best headphones for your needs, it’s important to know that looking at the headphone sensitivity as a specification of quality doesn’t worth much. All you need to check is that they have a value around 95dB or up, if you want something efficient.
What matters is that sensitivity is closely related to impedance which is highly important metric to look at when you try to choose your headphones based pairing them with other devices.
• Studio and Hi-Fi applications – High-quality headphones with higher impedance are mostly used in studios because professional audio equipments have large voltage swings which can overcome the noise produced by other electronic devices.
• Studio quality headphones and smart phone combination – If you already have high-impedance headphones you can use them with your smart phone or your portable music player without worrying that they can be damaged. What you can expect thou is that your battery life can increase, the distortion may decrease, noise can decrease too. The good thing is that if the playback level is loud enough then the overall sound quality may improve too.
• Low-impedance headphones and studio quality gear – Although this combination sounds more complicated, it doesn’t have to be if you follow your studio gear audio specification. Even thou some headphone amplifiers have overload protectors, improper usage may lead to overload and damage to your headphone amplifier.
We hope we answered most of the questions regarding the sensitivity of the headphones.
At the end it’s not about the specifications or the metrics of the headphones, it’s all about what kind of headphones will satisfy your needs.