Below are some details that you should know before buying a headphone.
Wired, Wireless, True Wireless
Older wireless headphones needed a separate dongle to send audio from the player. With the rise of Bluetooth headphones in recent years, fewer companies are producing older wireless models. Today’s Bluetooth headphones transmit a higher quality sound than models from a few years ago and have more freedom of action due to the lack of wires.
But if you want to buy high quality headphones, it is better to look for wired models. Wired headphones are usually connected to the player via a 3.5mm or 6.3mm jack. There are many types of jacks available on the market. The 2.5mm jacks are also gradually being forgotten, and there are fewer new devices or headphones with these jacks. Some headphones are also equipped with USB-C or Lightning ports, which are especially useful for people whose mobile phones do not have a 3.5 mm headphone port.
The more advanced models, known as True Wireless headphones, are designed as two delicate headphones without any wires. How these models connect to a mobile phone is usually that one headphone connects to the phone via Bluetooth and sends audio signals to another headphone. That’s why some of these completely wireless headphones (especially the low-cost models) suffer from problems such as delayed sound between the two phones or occasional sound or connection disconnections. Of course, some completely wireless models claim that each headphone has a separate mobile connection to minimize such problems. We should also mention that almost all completely wireless headphones come with a separate box that allows you to charge the phone several times.
Types of Headphones
Here are the types of headphones in terms of how they are placed inside or on the ear and the advantages and disadvantages of each.
These headphones sit inside the tulip and outside the ear canal; however, in some models, a small part of the headphones enters the duct and can reduce the penetration of noise outside into the ear. Many of these headphones come in a variety of sizes, including headphones, depending on the size of the ear. The advantages of these headphones are light weight, compact size and ease of transportation.
Bluetooth headphones come in a variety of sizes. Simple models are connected with a single wire, and the battery is usually located in a small space between the two headphones. The round neck models have a horseshoe-shaped section that accommodates the battery and the size of the sections, while the wires of the two headphones come out on both sides. These models, which are placed on the neck, may not be very comfortable for many users. These headphones also include earbuds, which are equipped with a call microphone and usually keys for controlling sound or music.
Advantages of In-ear Headphones:
Light and compact
Most models come with a dedicated microphone
Isolation of the sound in most of the models
Easy to use with glasses, hat, earrings and different hair style
Disadvantages of In-ear Headphones
Lower sound quality and weaker bass compared to round the ear models
Discomfort of the ear if used for a long time
Difficulty in wearing
Rotation of the wire problem in case of wired models
Lower battery life in Bluetooth models
These headphones are lighter than round the ear models and are more compact. Some users believe that these headphones are easier to put on the head and at the same time do not cause the problem of sweating around the ears in long-term use. On-ear headphones, like round the ear models, are available in open and closed back models, and they usually hear the outside sound more than round the ear models.
On-ear headphones can be folded down to take up less space when not in use. Wireless headphones use large batteries, which is why these types of headphones usually have more battery life than in-ear models.
Advantages of On-ear Headphones:
Portable and medium weight
Easier placement on the ear
Disadvantages of On-ear Headphones:
Improper noise insulation compared to models inside and outside the phone
Noise leaks out
The bass is weaker than on-ear models
Annoying of the ears of some users
Over-ear headphones cover the entire ear, and because of their larger size, they usually accommodate larger drivers. That’s why they produce louder sound and higher bass quality. In addition, because the drivers are located farther from the ear, a sound similar to speakers is produced.
The Advantages of Over-ear Headphones:
The best volume, the best quality and the highest bass compared to in-ear and on-ear headphones (depending on the model)
Some models are equipped with detachable cable and replaceable ear pieces.
Disadvantages of Over-ear Headphones:
Heavy for some users
Heating and sweating the ear in some models
Requiring amplifier in professional models with higher impedance
Not being able to use with glasses, earrings and some hair styles
We should also mention that the word headset refers to headphones that have a microphone. Handsfree is a wireless headset that is usually designed as a single earphone and more for talking on a mobile phone. Most handsfree devices are equipped with keys to answer or reject calls and change the volume.
Gaming headsets are specifically designed for gamers. Most gaming models are phone-type, but some companies, including 1More, also offer gaming headsets. Gaming headsets are usually designed to deliver the most detail needed in games to the user’s ears, but are usually not suitable for listening to music or watching movies.
Technical Terms of the Headphones
If you want to buy headphones, you have to learn some technical terms to choose the best headphone.
Drivers are the main part of a headphone and are responsible for converting electronic signals to sound. Drivers come in a variety of models, but almost all of them are made up of simple magnets, audio coils, and apertures. These components cause the diaphragm to vibrate, and eventually the vibrations reach our ears by producing sound waves.
When the driver is mentioned in the specifications of the headphones, the diameter of the aperture is in millimeters. In general, headphones with larger drivers usually produce better sound and are louder and have more powerful bass. In round the ear headphones, drivers larger than 40mm can be a good option.
But on-ear and in-ear headphones are usually smaller so they cannot have large drivers. That’s why many of them use dual (or triple) drivers. In this case, one of the drivers is usually responsible for producing bass sound and the other for producing medium to high frequency sounds.
Frequency Response Range
Frequency response range Indicates the range of audio frequencies that the headphones are capable of reproducing. The frequency response range is determined in Hertz. The low frequencies are related to the bass sounds and the high frequencies are related to the lower sounds (treble). The middle frequencies are also between the two. Most headphones claim a response frequency range of between 20 Hz and 20 kHz; That is, the amount that humans are able to hear.
Of course, these numbers are not good criteria for determining the quality of a headphone. However, they can help users choose the right headphones. For example, if you listen to songs with a lot of bass, you should look for headphones that can cover low frequencies.
Sensitivity and Sound Pressure Level (SPL)
Sensitivity and Sound Pressure Level (SPL) indicate how loud the headphones can play. However, it should be noted that the sensitivity is not a very good criterion for buying headphones; because manufacturers use different methods to measure it.
Sensitivity, more precisely, shows how loud a headphone produces for a certain amount of power. For example, if a headphone has a higher sensitivity per milliwatt (with a decibel unit in milliwatts or dB / mW), it means that it generally produces a louder sound. In other words, these headphones require less volume to produce a certain sound level. To understand the sensitivity, the sensitivity of 68 decibels is relatively low, and high-end headphones have a sensitivity of more than 110 decibels.
Sensitivity may also be expressed as “sound pressure level” or SPL. SPL is shown in terms of decibel SPL for milliwatts (or simply BS), but there is no absolute standard for it. Most headphones have an SPL range of 85 to 120 decibels. In normal city traffic, this rate is about 80 decibels, and in the case of human screaming, it reaches 105, and in the take-off, it reaches 130 decibels. A sound of about 120 decibels can damage the human ear. The US Occupational Safety and Health Administration believes that people who are exposed to more than 85 decibels of SPL may suffer serious hearing loss.
Higher sensitivity of the headphone can also lead to some problems. High-sensitivity headphones not only play music louder, but also make everything else heard. For example, the “hiss” sound produced by the amplifier or mobile phone circuits or electrical noise. This is very common in high sensitivity earbuds and it is easily heard. Of course, the quality of the amplifier also has an important effect on this issue.
This factor indicates the electrical resistance of the headphones in terms of ohms. Simply put, headphones with higher impedance require more power to produce sound due to more electrical resistance. Most headphones produced for mobile phones have low resistance (less than 32 ohms) and therefore consume less energy. But professional, high-end headphones have much higher impedance (up to 300 ohms or more). These headphones require a separate amplifier to produce sound.
The problem with low-impedance headphones is that although they operate at low voltages, they require high currents. The intensity of the electric current causes vibration and eventually noise. This can cause background noise such as “hiss” sound in these headphones. Different impedance issues in headphones can also cause other problems.
High-impedance headphones require a headphone amplifier.
For example, high-impedance headphones can’t be used directly with mobile phones. In addition, low-impedance headphones should not be connected to special amplifiers for professional headphones. That’s why choosing the right headphones for your audio system is so important. However, most headphones don’t have to worry about impedance; because most of them have low impedance and are suitable for use with most devices, including mobile phones and computers. The high impedance of professional headphones is usually clearly stated on their box or on the manufacturer’s website.
The total value of the harmonic distortion or THD (Total Harmonic Distortion) indicates the amount of noise disturbance that reaches the phone at high volumes. In headphones, sound is generated by the vibration of the aperture inside the driver. At high volumes, the diaphragm may not be able to vibrate at high speeds, which can cause distortion in the sound. The amount of THD is calculated based on the percentage and the lower the better. Most headphones today have a THD value of less than one percent, which is much lower in high-end models.
Bluetooth Audio Codecs
Bluetooth has limited bandwidth. In other words, high data rate can cause occasional or even intermittent interruptions. That’s why special codecs have been developed that, by compressing the information sent from the player to the Bluetooth headset, improve the quality of the sound heard while reducing latency and power consumption.
At the time of purchase, you should pay attention to what codecs the headphones support. On the other hand, you need to make sure that your phone also supports it. In other words, to take advantage of an advanced codec, both devices must be able to support it. For this reason, headphones that support a quality codec may give you low quality by connecting to an old phone; because both devices have to talk to each other with a simpler, lower-quality codec. The opposite is also true; this means that a low-quality, low-quality headphone has a low sound quality even when connected to an advanced phone with new codecs.
Information about audio codecs is usually posted on the headphone, mobile and mp3 player manufacturer’s site, as well as the headphone box. Most headphones as well as mobile phones support several different codecs. If you’re an iPhone user, it’s a good idea to choose models that support standards such as AAC among Bluetooth headphones. Of course, Apple AirPods is one of the best choices for these phones.
SBC is a mandatory standard for all Bluetooth devices that support A2DP. SBC has a data transfer rate of only 192 to 320 kbps and drastically reduces the quality.
Qualcomm has aptX series standards that include aptX LL, aptX Adaptive, aptX and aptX HD. Among these standards, only aptX LL supports very low latency of less than 40 milliseconds. The advantage of aptX over SBC is related to higher data rates. aptX has the ability to send at a rate of 352 Kbps, and in aptX HD this rate reaches 576. Although the quality is reduced by the standard, the sound is still high quality and the data is sent smoothly. aptX Adaptive is one of the new standards that allows you to change the data rate between 279 and 420 Kbps depending on the situation. This standard is not able to achieve the highest aptX HD rate, but according to Qualcomm, it is very optimal.
AAC is a standard that is free for companies to use and is one of Apple’s favorite standards. If you have an Android mobile, AAC is not very useful for you; because its performance is unreliable. In addition, Android is not yet optimized to work with this codec, which is why AAC consumes a lot of energy. However, iPhone users can enjoy high quality playback of this standard. The AAC data rate reaches 250 kbps, which is equivalent to a medium quality mp3.
Sony has a special standard similar to Qualcomm. The LDAC is Sony’s special audio codec that could theoretically send up to 390 kbps of data at up to 990 kbps. However, when it comes to sending data at 330 kbps, both SBC and aptX remove Sony from the field; Because many devices are compatible with these two standards. LDAC used to be limited to Sony products, but with the arrival of Android 8.0, it will be supported on many phones, and the Android Open Source Project (AOSP) now supports this standard.
LHDC is a low-delay, high-quality audio codec capable of sending at 900 kbps, or three times the SBC. This codec is currently supported on Android 10 and is part of the Android Open Source Project (AOSP). LLAC or LHDC LL is an alternative to LHDC that has lower latency and is ideal for gamers. This codec has the ability to send at a rate of 400 or 600 Mbps and its delay is up to 30 milliseconds.
The LE Bluetooth LC3 codec was introduced at CES2020 and promises to improve performance. One of the uses of this codec is to help people with hearing problems. In addition, it can be used in multiple audio streaming and simultaneous dual transmission to two Airbad phones via smartphones (two 80 Kbps per second instead of one 160 Kbps).
The Samsung Scalable Codec was introduced at the same time as the Samsung Galaxy Buds. This standard promises to reduce noise interruption problems and works best with Samsung phones with support for this feature. The Galaxy Buds Plus is one of the earbuds that supports this standard.
Open Back or Closed Back
Most of the round the ear or on-ear headphones are closed back. In these headphones, due to the closed back of the drivers, the sound of the headphones does not leak much, and at the same time, the path of sound entering the ear is blocked to a large extent. But in Open Back headphones, there is no obstacle to prevent the sound from leaking out, and the sound is heard outside.
Open-back models produce studio sound that is closer to reality and with the least amount of change, and can be used to record sound on the radio or singing in studios or mixing and mastering. But since the sound of these headphones leaks easily, they are not suitable for public places or offices.
Many headphones reduce the amount of noise that reaches the phone by isolating the ear. Some in-ear headphones prevent most of the noise from entering the ear by using the plastics on the headphones. Some round the ear models also prevent the entry of some noise by completely covering the area around the phone.
Active noise cancellation is a more advanced feature found on some expensive headphones. Headphones with this feature use microphones to detect ambient noise and prevent the sound of the environment from being heard by playing the opposite sound. However, unfortunately, there is no exact criterion for the quality of operation of this feature, but some brands, including Bose and Sony, had great improvements in this area.
Other Features of Headphones
Some headphones (especially expensive true wireless earbuds) are equipped with various sensors, including a gyroscope and an accelerometer. These sensors can help monitor sports activities or provide support for gestures to control music and more. Some headphones also use heart rate sensors and touch screens to control headphone capabilities.
Another feature of some expensive headphones is the “Hi-Res AUDIO” display, which indicates high-resolution audio playback. Headphones with this certificate have the ability to play audio up to 40 kHz or more. Let’s not forget that this rate is much higher than the maximum frequency that can be detected by humans, i.e. 20 kHz, and even with age, the maximum audible frequency of humans is less than this value.
Benefiting from this certification is not necessarily a reason for the superiority of headphones; because right now you can find many professional headphones on the market that are of very high quality and do not have Hi-Res AUDIO certification. That’s why some people think that headphones don’t care so much about the Hi-Res standard; especially if the music you give the phone is not Hi-Res.
If you’re in the habit of listening to music while exercising, it’s a good idea to choose headphones that are resistant to sweat. Some headphones (especially in-ear models) are water resistant and you can even swim with them. However, some headphones that are highly resistant to water do not have a good sound due to being equipped with protective layers and are unable to play some frequencies.
If you are planning to buy headphones for mobile phones, tablets, simple mp3 players or any other simple device without an amplifier, buying high-impedance headphones is not recommended at all; because such devices usually do not have the ability to play the right sound.
Sound Taste; a Personal Issue
Buying headphones is a very personal issue; because each person’s sound tastes are different, and opinions are very diverse. Some may prefer a high-bass sound and don’t care about the accuracy of the sound. For others, the volume may be more important. Some people choose only flat headphones that are closer to reality. Finally, we suggest that if the sound quality is your top priority, listen to the sound of your favorite headphones before you buy.