Impedance
Impedance refers to the headphone's nominal resistance to AC current, such as an audio signal.
Other things being equal, a higher impedance reduces distortion, but requires a more powerful amplifier — otherwise the headphones simply will not be able to produce sufficient volume. Thus, the choice of resistance depends primarily on which signal source you plan to connect the "ears". So, for a portable gadget (smartphone, pocket player), an indicator of
16 ohms or less is considered optimal,
17 – 32 ohms is not bad. Higher values —
33 – 64 ohms and
65 – 96 ohms — will require quite powerful amplifiers, like those used in computers and televisions. And models with a resistance of
96 – 250 ohms and
above are designed mainly for Hi-End audio equipment and professional use; for such cases, detailed recommendations for selection can be found in special sources.
Frequency range
The range of sound frequencies that headphones can reproduce.
The
wider this range, the more fully the headphones reproduce the spectrum of sound frequencies, the lower the likelihood that too low or too high frequencies will be inaccessible. However, there are some nuances to consider here. First of all, let us remind you that the perceptual range of the human ear is on average from 16 Hz to 22 kHz, and for the complete picture it is enough for headphones to cover this range. However, modern models can significantly exceed these boundaries: in many devices the lower threshold
does not exceed 15 Hz, or even
10 Hz, and the upper limit can reach
25 kHz,
30 kHz and even
more. Such wide ranges in themselves do not provide practical advantages, but they usually indicate a high class of headphones, and are sometimes given only for advertising purposes.
The second important point is that a wide frequency range in itself is not a guarantee of good sound: sound quality also depends on a number of parameters, primarily the amplitude-frequency response of the headphones.
Sensitivity
Rated headphone sensitivity. Technically, this is the volume at which they sound when a certain standard signal from the amplifier is connected to them. Thus, sensitivity is one of the parameters that determine the overall volume of the headphones: the higher it is, the louder the sound will be with the same input signal level and other things being equal. However, we must not forget that the volume level also depends on the resistance (impedance, see above); moreover, it is worth choosing “ears” for a specific device first by impedance, and only then by sensitivity. In this case, one parameter can be compensated for by another: for example, a model with high resistance and high sensitivity can work even on a relatively weak amplifier.
As for specific figures, headphones with indicators of 100 dB or less are designed mainly for use in a quiet environment (in some similar models, the sensitivity
does not exceed 90 dB). For use on the street, in transport and other similar conditions, it is desirable to have more sensitive headphones — about
101 – 105 dB, or even
110 dB. And in some models, this figure can reach
116 – 120 dB. and even
more.
It is also worth noting that this parameter is relevant only for a wired connection according to the analogue standard — for example, via a 3.5 mm mini-
...jack. When using digital interfaces like USB and wireless channels like Bluetooth, the sound is processed in the built-in headphone converter, and if you plan to mainly use this kind of application, you can not pay much attention to sensitivity.Microphone
The location of the
microphone, which the headphones are equipped with (if available, of course).
— On the cable. A microphone installed on the headphone connection wire (or on the connection cable in non-TWS wireless headphones). Can be combined with
volume control. This option allows you to separate the microphone and headphones, reducing the weight and dimensions of the "ears" themselves; on the other hand, the microphone when worn is often quite far from the face, which can be inconvenient. Therefore, this design is mainly used among earbuds and in-ear
headphones, where the size of the "ears" is critical.
— Built into the body. A microphone located in the housing of one of the headphones. This arrangement is convenient because there are no extra protruding parts outside (as in
headphones without a microphone), while the microphone is close to the face, and in some models it is also able to perceive sound according to the principle of bone conduction. However installation in close proximity to the speaker gives additional interference and may degrade the quality of voice transmission. However, these shortcomings are not critical: interference can be compensated, and the built-in headphone microphones, in fact, do not need perfect sound transmission accuracy. Therefore, this option is quite popular nowadays, and it is fo
...und not only in miniature models, for which the absence of unnecessary details on the outside is important, but also in rather large overhead "ears".
— On the bow. A microphone mounted on a small boom that is attached to one of the headphones. The microphone on the bow is the most popular among overhead headphones: a large cup can be supplemented with a boom without sacrificing convenience, and the microphone itself is located far from the headphones, which has a positive effect on the purity of the sound. The boom often has a swivel or detachable mount, which allows you to remove the microphone from the face until it is needed (by lifting the boom vertically along the headband).
— Retractable on the bow. Headband microphone (see above) with a retractable design: the headband can be pulled out of the cup when needed and can be tucked back inside when not in use. These headphones are more compact and have a neater appearance than models with a headband on a swivel mount: in a hidden position, the microphone takes up almost no space outside. The retractable microphone design is especially popular in gaming models (see “Intended Use”): in single-player games where you do not need to communicate with comrades, the microphone can be folded compactly.
— Removable on the shackle. Headband microphone (see above), which can be completely detached from the headphones if desired. Such a design can be useful, for example, if the “ears” are used both as gaming and as “marching and musical”: in a multiplayer game, the microphone is indispensable, and for listening to music outside the home, it can be removed so as not to carry extra equipment (which besides, you can lose).
— At the receiver. A variant used in wireless headphones with a separate receiver. In terms of design and use, it is similar to the microphone on the cable described above: on the one hand, the headphones themselves can be very light and tiny, on the other hand, the microphone may not be located close enough to the face, and when talking it will have to be brought closer.
— In the mount. In this case, most often means a microphone mounted on a neck mount (see below). This option is found mainly among wireless headphones, which have a signal receiver in the same mount. Such a microphone is located close to the neck, which allows you to achieve good speech intelligibility and at the same time cut off extraneous sounds even without any special additional tricks.
— On the cable and in the case. Headphones equipped with two microphones — one in the case, the other on the cable. The features of these variants are described in detail above. Here we note that their combination is extremely rare, mainly among high-quality "ears" with a combined connection (see "Type of connection"). In such models, when working via a wireless channel, a microphone in the case is used, and when connecting a wire, a microphone on a cable is used, which is less susceptible to interference.
— On cable and removable. Another kind of headphones with two microphones, also quite rare. One microphone in such models is mounted on a cable, the second — on a detachable bow. See above for more on each of these options, and combining them allows you to tailor the headphones to the specific situation. For example, the bow is very convenient for voice communication at home or office computers, but on the street and in transport it is better to remove it and use the microphone on the cable.
— In the case and removable. A rather rare and non-standard option is the combination of a microphone in the case and a microphone on a detachable bow. See above for more details on each of these varieties, and their combination is used quite rarely — in separate premium gaming models with a combined connection. The main point in this case is that it is more convenient to use a removable microphone in one place, with a wired connection, and in the “mobile” wireless mode it is better to remove it and get by with the built-in microphone. However, such features are fundamental mainly for the most demanding users, so this option has not gained distribution.Microphone noise canceling
The presence of a noise reduction system in its own headphone microphone.
In accordance with the name, such a system is designed to eliminate extraneous noise - primarily during conversations. It is usually based on an electronic filter that passes the sound of a human voice and cuts off background sounds such as city noise, the rumble of wind in the microphone grille, etc. As a result, even in noisy environments, thanks to the
noise reduction of the microphone, speech is clear and intelligible; True, the system inevitably introduces distortions into the final sound, but they are not critical in this case.
— ENC. ENC (Environment Noise Cancellation) technology significantly reduces ambient noise with directional microphones. It is used both in gaming devices so that gamers can easily communicate in voice chat, and in TWS earphone models so that you can comfortably talk on the phone in a noisy environment.
— cVc. Microphone noise reduction cVc (Clear Voice Capture) is an advanced technology that is found mainly in expensive headphone models. cVc algorithms effectively suppress echo and noise from the environment. Sound processing using this technology is carried out at several levels at once - the algorithm determines the reference signal-to-noise level, automatically adjusts speech to the desired volume level, applies adaptive equalizers to process the entire voice, as well as specialized filters to remove
...low-frequency bubbling, sibilants and hissing.Noise cancellation
A system that reduces the influence of ambient noise on the audibility of sound through headphones. "Noise reduction" with the help of a separate microphone (or several micro) "listens" to external sounds and sends the same sounds to the headphones, but in antiphase. Due to this, the noise heard by the ears is attenuated almost to zero and the user can enjoy the sound of the headphones without interference even in a rather “loud” environment. For filtering in headphones, Active Noise Cancellation (ANC) and Environment Noise Cancellation (ENC) systems are used. The first suppresses all the noise around the listener, the second - reduces the noise level of the environment.
Active noise cancellation affects the purity of the sound, but the noise from the outside spoils the picture when listening to audio tracks even more.
Also in the headphones there is an adaptive active noise reduction system Adaptive ANC, aimed at automatically adjusting the sound of the headphones depending on the level of ambient noise. In a noisy environment (for example, when traveling on the subway), the Adaptive ANC system enhances the work of “noise reduction”, in the absence of loud sounds from outside, it weakens the noise reduction.
Headphone battery capacity
The capacity of the battery installed in the headphones of the corresponding design (see "Power").
Theoretically, a higher capacity allows to achieve greater battery life, but in fact, the operating time also depends on the power consumption of the headphones — and it can be very different, depending on the characteristics and design features. So this parameter is secondary, and when choosing it is worth paying attention not so much to the battery capacity, but to the directly claimed operating time (see below).
Charging time
The time required to fully charge the battery in properly powered headphones (see above).
In this case, we mean the battery charging time from 0 to 100% when using a standard charger (or a third-party charger with identical characteristics). Accordingly, in fact, this indicator may differ from the claimed one, depending on the specifics of the situation. However, in general, it is quite possible to evaluate different models and compare them with each other: headphones with a shorter claimed charging time will in fact charge faster (ceteris paribus).
Also note that an increase in battery capacity (and headphone battery life) inevitably implies an increase in charging time. To compensate for this moment, special fast charging technologies can be used — however, they affect the cost and require the use of specialized charger.
Operating time (music)
The declared operating time of headphones with autonomous power supply (see above) when listening to music on a single battery charge or a set of batteries.
As a rule, the characteristics indicate a certain average operating time in music listening mode, for standard conditions; in practice, it will depend on the intensity of use, volume level and other operating parameters, and in models with replaceable batteries - also on the quality of specific batteries. However, based on the stated time, you can fairly reliably assess the autonomy of the selected headphones and compare them with other models. As for specific values, relatively “short-lived” devices have a battery life
of up to 8 hours, a figure of
8 – 12 hours can be called quite good,
12 – 20 hours – very good, and in the most “long-lasting” headphones the operating time can
exceed 20 hours.