2021-11-30

Timothy Hsu, an acoustic expert, gives you an in-depth understanding of which “three elements” to pay attention to when selecting headphones?

By yqqlm yqqlm

Visit: Alibaba cloud 11.11 cloud Carnival activity hall

7bbcf6ff4020069 - Timothy Hsu, an acoustic expert, gives you an in-depth understanding of which "three elements" to pay attention to when selecting headphones?

first talk about “sound wave”: in physics, sound is generated by air vibration composed of a series of high and low pressure areas, which is also the cycle of sound wave

the number of cycles per second is calculated to determine the frequency or pitch of the sound. Scientists use Hertz (Hz) as a description unit of frequency. 500 Hz audio means that sound will experience 500 complete high and low pressure cycles per second

the loudness or amplitude of the sound is determined by the maximum pressure of the wave. The higher the sound pressure, the greater the volume

in order to generate sound, the headset needs to convert the electrical audio signal into a frequency that can be distinguished by the human ear and create a corresponding high / low voltage cycle

Timothy Hsu, an acoustic expert, gives you an in-depth understanding of which “three elements” to pay attention to when selecting headphones?

next, talk about the human ear: as shown in the above figure, the human ear system is very complex. Its main function is to convert the vibration of air into electrical signals and send them to the brain. As an incredible biosensor, ordinary people can distinguish a wide range of pitch and different levels of loudness

when a sound enters the ear, your periosteum will convert the air vibration into a small mechanical vibration of the middle ear bone. These mechanical vibrations become fluid vibrations in the inner ear, and then sensitive nerves convert them into acoustic and electrical signals that can be understood by the brain

it should be pointed out that although human ears can perceive 20Hz – 20kHz sound, human hearing is not equally sensitive at all frequencies. Take low-frequency rumbling and high pitched bird singing as examples. Even if they have the same loudness, we will still think that the former is more “quiet”

in other words, human ears are more sensitive to intermediate frequency than high and low frequency. The researchers believe that this may be the result of long-term evolution of nature, and ordinary people don’t need to know more about it. But for headphone engineers, the difference between human perception and pure physics must be taken into account

Timothy Hsu, an acoustic expert, gives you an in-depth understanding of which “three elements” to pay attention to when selecting headphones?(1)

then the working principle of the headset: as shown in the above figure, the speaker is basically composed of (1) magnet, (2) winding wire, (4) diaphragm and (3) suspension supporting diaphragm

the essence of headphones, whether headphones or earplugs, is small speakers. But compared with human ears, speakers work the opposite way – they convert the input electrical signal back into vibration in the air

electromagnetism points out that when the wire is wound around the magnet and the current in the wire changes, the surrounding magnetic field will change proportionally. When the electrical signal of a song or podcast passes through the wire pulse in the headset, it will change the current and drive the magnet

in this way, the magnet will push the diaphragm to move, push and compress the air to generate high and low pressure amplitude pulses, and finally convert them into music we can hear

ideally, the speaker will perfectly reproduce the input electrical signal. But in the real physical world, this process still has its limitations

factors such as the size / material of magnets and diaphragm will cause inevitable distortion, resulting in some frequencies being louder or softer than the original signal

Timothy Hsu, an acoustic expert, gives you an in-depth understanding of which “three elements” to pay attention to when selecting headphones?(2)

to sum up: Although no headset can perfectly reproduce the signal, we have countless different ways to “distort” the signal. If you get different feelings on two equally expensive headphones, it has a lot to do with the tuning preferences of different manufacturers

● when engineers are developing new earphones, they should not only consider the’distortion’ effect of human hearing on sound, but also consider the physical limitations of speakers. ● your favorite timbre and high, middle and low frequency tuning (as well as factors such as age, experience, culture / music genre preference) also directly affect the evaluation of a headset

take hip-hop music as an example, this part of the audience may prefer heavy bass performance. But for classical music lovers, they want to get less frequency distortion

however, the faithful restoration of sound (or entertainment tendency) is difficult to achieve both. For example, in the scenario of focusing on speech understanding, some products may pay more attention to the frequency response performance of 1000 ~ 5000 Hz

of course, we can also design so-called “hip hop headphones” for people with hearing impairment. Just to ordinary people, the same product will be another evaluation

in a word, what kind of headphones you want to buy depends on the specific scenarios you use. After all, only from the perspective of headset design can you know that this matter is closely related to science, art and experience