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.
Speaker size
The diameter of the speaker installed in the headphones; models with multiple drivers (see "Number of drivers"), usually, the size of the largest speaker is taken into account, other dimensions can be specified in the notes.
In general, this parameter is relevant primarily for over-ear headphones (see "Design"). In them, emitters can have different sizes; the larger it is, the more saturated the sound is and the better the speaker reproduces the bass, however, large emitters have a corresponding effect on the dimensions, weight and price of the headphones. But in-ear "ears" and earbuds, by definition, have very small speakers, and rich bass in them is achieved due to other design features.
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).
Case battery capacity
The capacity of the battery installed in the case (case) for headphones.
This parameter is relevant only for true wireless models (see "Cable type"). Recall that these headphones are charged from a case, which is usually equipped with its own battery and actually works in standalone power bank mode. Knowing the capacity of the battery in the case and in the headphones, you can estimate how many charges of the “ears” will last for one charge of the case. However, it should be taken into account that in the process of charging the headphones, part of the energy is inevitably spent on third-party losses, and the effective capacity of the case turns out to be somewhere 1.6 times less than the claimed one. This is the starting point for calculations: for example, a 300 mAh case will actually be able to transfer 300 / 1.6 = 187 mAh of energy to the headphones, and 30 mAh “ears” from such a battery can be fully charged about 6 times (187 / 30 ≈ 6).
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.
Operating time (with case)
The maximum operating time of TWS headphones, taking into account recharging with a native case. But this time is not continuous use, it takes into account breaks for "refueling". Anyway, this parameter allows you to understand for how long you can leave the network (for example, how many nights to spend in a tent to the accompaniment of your favorite artist).
Touch control
This feature means that the controls in the headphones are not traditional buttons that you need to press, but sensors that are triggered by touch.
Touch control is somewhat more expensive than push-button control, but it has a number of advantages over it. Firstly, it gives the headphones a neat and technological appearance, with a minimum of protruding parts. Secondly, due to the absence of moving parts, the sensors are more reliable and compact. Thirdly, it is purely physically more convenient to use them, especially with the small size of the headphones. These moments are especially relevant for the "ears" of the true wireless format (see "Type of cable"), so it is in them that touch control is most often found. However, there are exceptions to this rule. Also note that the difference in price between buttons and sensors is often almost imperceptible compared to the cost of headphones in general.
Waterproof
The headphones have special protection against moisture and dust; also, this clause may specify the level of such protection according to the IP standard.
Not all
waterproof headphones allow complete immersion in water, but in this case this is usually not required — water protection is mainly intended for safe operation in the rain (or during sports activities when the user sweats a lot). But the specific degree of such protection in different models can vary markedly, and here it is most convenient to evaluate it by IP marking. This marking consists of the letters IP and two numbers; moisture resistance is described by the second, last digit, and in modern headphones you can find the following options:
— 2. Protection against vertical drops of water in the working position and when the device deviates up to 15 ° from this position. The minimum indicator that allows us to talk about resistance to rain (however, without strong winds).
— 3. Protection against splashes falling vertically or at an angle up to 60° from the vertical. Provides resistance to moderate rain and strong winds.
—
4. Splash proof from any direction. With such headphones, rain of medium intensity is not terrible, regardless of the strength of the wind.
—
5. Protected against water jets from any direction. Allows you to transfer already a combination of strong wind w
...ith a downpour.
— 6. Protection against strong water jets. It is considered the minimum level that allows you to swim safely (with your head above the surface of the water) wearing headphones.
— 7. Possibility of short-term (less than half an hour) immersion under water to a shallow depth (less than 1 m); continuous operation in immersed mode is not expected. In such headphones, you can no longer only swim, but also dive under water to a shallow depth (plunge with your head), but they are not suitable for full-fledged diving.
— 8. The highest level of water protection actually found in modern headphones (although theoretically there is a higher level, level 9). Allows long-term (more than 30 minutes) immersion under water to a depth of 1 m or more, and even permanent work in a submerged position. And although the latter is not particularly relevant for headphones, however, this degree of protection makes it possible to swim and even dive safely. However, note that specific restrictions on use in such headphones may be different, they must be clarified according to the instructions.
As for protection against dust (it is indicated by the first digit in the IP marking), its level in modern “ears” is indicated mainly in cases where it corresponds to level 4 (protection against objects 1 mm thick or more), 5 (allowed a small amount of dust that does not affect the operation of the device) or 6 (complete protection against dust). Also note that this number can be replaced by the letter "X" — for example, IPX7; this means that no official dust certification has been carried out for this model. However, this resistance in many cases can be assessed by the degree of protection against moisture: for example, devices with a moisture resistance of 7 or 8, by definition, do not let water through — which means that they are also not afraid of dust.
