Headphone characteristics – Reading and Understanding Them
Technical characteristics of the headphones can be found on their packaging, in the accompanying documentation, on forums and various test sites, as well as in product descriptions in online stores. Of course, they carry useful information, but for a layman they are often just numbers, and then it seems that the larger these numbers, the better. It is worth, finally, to figure out what these numbers mean, which characteristics are the main ones, and which are just a tribute to fashion and the gods of marketing.
Let’s figure out the main characteristics of headphones that will help you make the right choice of a specific headphone model that suits your musical preferences and the music equipment you use.
- The main characteristics of the headphones are:
- Amplitude-frequency characteristic (AFC)
- frequency range
- Maximum power
1. Frequency response (AFC) of headphone
And CH – these three letters have probably been seen by everyone who has read reviews of musical equipment or a description of headphones and microphones at least once. It’s very rare to see the frequency response on the headphone box or in the attached documentation. So you can find the frequency response on special sites with reviews of specific headphone models. Why know the frequency response and what is it all about? In a nutshell, the frequency response is a graph showing the dependence of the volume of a sound on its frequency.
It will become clearer if you look at the figure, where the horizontal axis shows the frequency of the sound signal (and frequency intervals with names), and the vertical axis shows the sound pressure level (volume).
By the shape of the frequency response, you can predict what the headphones will be in terms of tonal sound:
- the so-called “dark” (emphasis on low frequencies and lower mids, decay on high frequencies),
- “Light” (no fall at HF, rise in the upper middle),
- “Bright” (rise in the upper middle and at the HF).
From the frequency response, you can also see the boundaries of the frequency range – those frequencies at which the final drops in the frequency response occur on both sides. The shape of the frequency response curve depends on the measurement technique and the measuring stand.
Choosing headphones for frequency response
1. We select for ourselves several models that we liked by any criterion.
2. Determine what tonal coloring we want to get and what frequency range to amplify, based on their musical preferences (bass, vocals, etc.).
3. We find the frequency response of the selected models on the Internet and study it. For bass boost, there should be a boost in the midbass and a late decay in the lower bass. For emphasis on vocals – the middle without peaks and sharp drops. If you need headphones for vocals, then the mids should be without large peaks and valleys. For pronounced high frequencies – a late fall on and a relatively flat area at the top.
If the type of frequency response in a certain range does not suit you, keep in mind the following:
- Very narrow peaks and troughs may be just a defect in the measuring stand and not reflect the real picture.
- The frequency response at high frequencies can be wavy, the main thing is that there are no wide pits and hills.
Sensitivity characterizes the volume of the headphones depending on the level of the supplied audio signal. Sensitivity can be in the following units: dB / mW or dB / V, that is, the sound pressure level referred to milliwatts (input signal power) or volts (applied voltage). Of course, numerical values expressed in different units of measurement will differ, but they can be recalculated relative to each other (see table).
The higher the sensitivity, the louder the sound will be in them, even with a small input signal level. Low sensitivity headphones are usually quiet and require connection to high power sources.
It is more convenient to use the sensitivity value, expressed in dB / V, since it can be taken directly from the frequency response, and also to evaluate the change in the sound volume in the headphones when adjusting the source volume (applied voltage).
The sensitivity of specific headphones can be determined:
- for a certain frequency,
- average in a certain frequency range,
- maximum in a certain frequency range.
Usually the frequency response is uneven, therefore, the average sensitivity in the frequency range is often used.
High sensitivity, by the way, does not guarantee high sound quality at all. It’s just that at high sensitivity, you can use a source at low power, that is, at a low volume, the source itself sounds better, of higher quality. Therefore, using headphones with high sensitivity, you get loud and high-quality sound from a source that does not operate at the volume limit.
Thus, high-sensitivity headphones sound louder than low-sensitivity headphones, however, headphone impedance plays an important role.
Impedance is the nominal impedance at the headphone input. This parameter also affects the volume of the headphones, albeit to a lesser extent than the sensitivity.
The scheme for selecting headphones by their impedance is simple: the higher the signal source voltage, the higher the headphone resistance should be. Thus, for portable headphones (which are used for players, tablets, phones, etc.), you can get by with an impedance value of 32 ohms, if you use an amplifier, choose headphones with an impedance of up to 100 ohms, if you have very powerful equipment, then the impedance of headphones (high impedance) should be matched to its parameters. Just remember that high impedance headphone sound will not please you with a low voltage source. The higher the impedance of the headphones, the lower the sensitivity to voltage, which explains why low impedance headphones are louder, while high impedance ones require a separate amplifier.
4. The frequency range of the headphones
The human ear perceives sound in the frequency range of 20 – 20,000 Hz, but this is ideal. With age, the upper limit decreases for everyone, and for those people who are often exposed to noise (work, loud music, etc.), the hearing range is rapidly and significantly narrowed, again due to high frequencies.
By finding a hearing test on the Internet, you can easily determine your limits of hearing. Just for the sake of interest, because this information is unlikely to be useful to you in choosing headphones, unless it warns against listening to music too loud in the future. You can read more about hearing hygiene here .
Most often, the description indicates the same standard range of 20 – 20,000 Hz, and this is just a reply from the manufacturer. But if the deviations of loudness in the range are indicated, this is already a characteristic of the headphones. For example, if the description claims 20 – 20,000 Hz ± 6 dB, this means that the frequency response of the headphones fluctuates in the 6 dB range (along the vertical axis) in the specified frequency range. And this, in turn, means that there are no sharp peaks and dips in this range.
Thus, having seen the declared range of 10 – 25000 Hz, you should understand that almost always this is nothing more than a marketing ploy, you will not hear frequencies that go beyond the audible range. But there are exceptions: the underestimated lower limit of the frequency range leaves hope for the presence of sub-bass in the headphones (if the manufacturer was not lying), and the overestimation of the upper limit is justified for wireless headphones, when there are distortions and codec noise in this HF region.
5. Maximum power
You can also find such a characteristic in the description of the headphones. But it is very ambiguous and it can be interpreted in different ways:
- the maximum power at which the sound is not distorted,
- the maximum power at which the elements of the headphones will not be damaged (membrane, coil, etc.),
- analogue of audio signal power.
That is, this is an uninformative characteristic by which one cannot judge the volume of headphones, for example.
6. Features of Wireless Bluetooth Headphones
The most important characteristics (read the advantages) of wireless headphones are the following:
- aptX (HD), LDAC, AAC and SBC codecs;
- Bluetooth version from 4.0, or better from 5.0;
- autonomy of work from 10 hours;
- the presence of noise reduction.
Some more features of the characteristics of wireless headphones:
- Expanded high-frequency range to hide wireless noise. But sometimes it’s just a manufacturer’s gimmick.
- The impedance of wireless headphones does not convey any useful information for the buyer, so you can not look at it.
- Sensitivity is no longer an accurate indicator of volume, since other parameters of the wireless connection also affect the volume of the headphones.
We hope that you have got a general idea of the main characteristics that can be useful to you when choosing a headphone model. You can trust the numbers and graphs if they are taken from sites that specialize in testing and verifying the characteristics of musical equipment.
There are no clear standards for measuring the parameters of headphones, the characteristics and frequency response graphs depend on the measuring stands, manufacturers can indicate the values in different units of measurement – all this can lead to a mess in the head. Therefore, the main selection criterion is still your hearing, and the numbers are sometimes just a marketing ploy.
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