You absolutely don't know the cold knowledge of headphones!

In the use of headphones, everyone has a set of cognitions, even if they misunderstood, and then misrepresented this less correct cognition to others. The author encountered some earphone products in his work, so he wrote this article and gave it to colleagues for reference.

Know the human ear


First of all, we must first understand the listening characteristics of the human ear. Our normal human ear can obtain the following picture according to the sound pressure after listening to the audible frequency. We use the simplest explanation to explain the chart. From left to right is the response of the human ear listening to the sound (bass to treble), from bottom to top is the size of the sound (loudness).


Red is the listening curve in recent years, but this is a side effect of environmental civilization, or the early experimental equipment is not accurate. In short, after re-evaluating the characteristics of the modern human ear, it can only be said that the ears of modern people listen to low frequencies. Acumen is less sensible than the people of the past.


After some concepts of the human ear chart, we can clearly understand that the sensitivity of the human ear to the low frequency is not very good under the sound pressure (about 84 decibel position), and the hearing sensitivity value of the middle and high frequency band is about 10 Decibel up and down, so in the production of a headset, for the normal normal human ear listening curve, the headset product itself must require some equalization (equal) adjustment, which is a delicate process, and also determines the level of the headset product.

Cover earphone

The frequency response curves of the cover headphones are slightly changed from the popular 20 Hz (low frequency) to 20000 Hz (high frequency) almost equalization. In fact, these micro equalization curve corrections are mostly used in the cover. In the type of earphone products, this is because there is still some distance between the earphone type earphone and the ear ear canal, so it is necessary to do the personality in the direction of the environment listening to the environment to listen well.

Because the cover type earphones have a large space for the voice coil diaphragm unit, the diameter of the voice coil diaphragm design is relatively large, and the low frequency generated by the large voice coil work is advantageous for these small inner ear type earphones, but It is not a low-frequency condition, and the superior is better than everything. On the contrary, when the cover of the cover-type earphone is combined with the voice coil of the voiced sound, the box sound and the resonance of the frequency point are generated, which is an effective formation of a headset for the merchant. Before, the most must be considered and concerned, because any change will determine the future personality and listening level of this headset.


Look at the picture


SONY_MDR_CD9000ST


This is the isoacoustic curve observation table of the earphone. The same from left to right is the characteristic display of the frequency response. From low to high, it is the impedance meter display. The higher the resistance value, the smaller the sound, and the opposite is more sensitive.


This is the headphone feature of SONY_MDR_CD9000ST. It can be seen from the graph that it has a relatively high impedance at about 100Hz, that is, the frequency domain near 100Hz, its energy will be lower, and the frequency band around the high frequency 3KHz is also impedance. These are too high, these adjustments are also to match the human ear because of the formation of the ear canal structure, the most sensitive position in the 3 ~ 4KHz position (observation of the human ear can be seen in the chart), so it will converge this band appropriately energy of.


Ex-topic: Do you see that the impedance of the earphones is different? I have repeated the test several times. The final result explanation should be that this earphone has been alive for several years at the work site, right ear. The magnetic flux Gauss ratio is probably aging, so the impedance is measured to be about one ohm, but can you hear it?

SENNHEISER_HD25II


This is the famous working earphone of SENNHEISER_HD25II. The small earmuffs are not big. Its equal-impedance curve shows a small convergence near the frequency band slightly higher than 100Hz. The high-frequency position is raised a little near the 5KHz band to beautify. The rendering of crisp sounds.


AKG_K450


This is the small earmuff earphone of AKG_K450. For the low frequency and other words, the 50Hz is attenuated a lot. The left and right ears are somewhat disproportionate at the 3~4KHz position. This earphone is also on the scene and continues to operate without stopping. Fine, but can you hear it?

AKG_K1000


The cover-type earphone finally posted a classic AKG_K1000, which is a respectable product in the world of sound. It is also known as a speaker worn on the head. It has moderate convergence around 80Hz, and a medium-high frequency has a big The energy attenuation of the interval is around 5KHz, and the difference between the two ohms is the most.



Due to the progress of the coil and high-sensitivity diaphragm material process, a large number of human resources and material resources are put into research and development and production. Today, the general manufacturing technology of such small earphones has been produced everywhere.


When the small earphones are used for sub-segmentation, there are small earphones that are placed in the external auditory canal and have deeper inner ear, such as hearing aids or eardrums. Through the contents of the preceding text and pictures, the more the finishing project of listening, the deeper the ear, the more it is necessary to wait for the listening curve of the earphone to be inaudible. If the small earphone itself is not equalized. The process, then must be handled by the winding equipment, the relative must be expensive and not low.


The small headphones that are commonly used in the industry also show their characteristics, and use observation to understand why the price of these small headphones will remain high.

This does not mean that the iPhone comes with a headset that is inferior, but the difference in the perception of different application environments. In addition, the cover-type headphones that are commonly used in the production process are moderately increased in the requirements of the sound curve equalization and the dynamic design. Some low frequencies meet the bass requirements of the human ear's low sound pressure listening. Sometimes when we listen to music at a small volume, we always feel that the low frequency is insufficient. This is because when the human ear whispers, the sensitivity to the low frequency is blunt. I feel it when I open it loudly, but I am too noisy. A friend with similar situations can look for a music playback application with sound quality adjustment. When listening to it, you can try to increase the low frequency between 80~160. 10 decibels, it is very easy to listen to, the other is to replace the low frequency equal curve with increased headphones, the general DJ dedicated earphone curve mostly increase the dynamics of the low frequency band, which is more expensive, the other is DIY Wait for the circuit, buy a small box, do not occupy the space of the carry-on bag, through a simple equal circuit can get a satisfactory 10 dB low frequency in the low volume.
Further in the home Hi-Fi product circle, the cover type earphones use multiple voice coils to utilize the phase deviation technique to create the listening quality of the sound body, and usually the code box is entrained. (Any picture of any headset can be found by typing a name on Google's image search page.)

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