Cable supply
How to connect the cable to the headphones.
— One-
sided. In such models, the wire is connected to only one earphone. This option is more comfortable and less prone to tangling, but the headphones must have a headband or neck mount so that there is somewhere to hide the wire that goes to the second ear.
—
Bilateral. In such models, a wire is connected to each “ear” separately (the cable for this is usually “forked” closer to the headphones, and sometimes at the plug itself). This is the only option technically available for headphones without a headband or neckband. At the same time, overhead "ears" with a headband can also be made bilateral — in particular, high-end hi-fi and hi-end models, where such a design is provided in order to reduce the influence of wires on each other.
Cable length
The length of the cable supplied with the headphones with the appropriate connectivity.
The optimal cable length depends on the planned format of the "ears". So, for pocket gadgets,
1 metre or less is often enough, for a computer it is already desirable to have a wire for
1 – 2 m, and preferably
2 – 3 m. And models with a longer cable length —
3 – 5 m or even
more — are mainly designed for specific tasks, such as connecting to a TV or using in recording studios.
Recall that in some models the cable is removable (see below) and can be replaced if necessary with a longer or shorter one. Also note that there are extension cables that allow you to increase the length of the main wire; such a cable may even be included in the delivery, this point (and the length of the additional cable) is usually specified in the notes.
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.Frequency range
The range of audio frequencies that the headphone's own microphone can normally "hear".
Theoretically, the wider this range, the more advanced and high-quality the microphone is, the closer the sound transmitted by it is to the real one. In fact, extensive frequency coverage is not always required. So, the working range of the human ear is about 16 – 22,000 Hz, and even then not everyone hears its upper part. And human speech usually covers frequencies from 500 Hz to 2 kHz, at least this range is considered quite sufficient for its transmission. So if you need a microphone for simple tasks like voice communication on the Internet or game chat, you can not pay much attention to the frequency range: even in the most modest models, it is more than sufficient for normal speech transmission.
Sensitivity
The sensitivity of the headphone's own microphone.
The more sensitive the microphone, the higher the signal level from it, at the same sound volume, and the better this model is suitable for picking up quiet sounds. Conversely, low sensitivity filters out background noise. At the same time, we note that these nuances are important mainly in professional work with sound. And for simple tasks like voice communication over the phone or via the Internet, sensitivity does not really matter: in headphones of this specialization, it is selected in such a way as to ensure that the microphone is guaranteed to work.
Flexible design
This feature usually means that the microphone is attached to the headphones using a special flexible arm.
The flexible design gives additional possibilities for moving the microphone relative to the user's mouth and makes it easier to choose the optimal position that provides the best sound quality.