5 reasons why different people evaluate the sound of headphones differently

Of all the types of audio devices with which I dealt, difficulties arose only with headphones. In many of the panel tests that I conducted for Sound & Vision, and those that I spend now for The Wirecutter, there are huge differences in the perception of the sound of certain headphones by different people. After reading the reviews and comments, you can see that there are more different opinions than it seems. Even excluding the opinions of the "trolls", it is still obvious that different people hear sounds in different ways.

There are several reasons for this. I described one of them several months ago in the article “Why headphones sound differently for different people. Part 1". I promised that I would write part 2, and now I did it. Part 1 was lost in the course of the ongoing reconstruction of the About.com site, so I will quote it later in this article.
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There is no pair of identical ears.

Reason 1: The auditory canals are very different.

Jacob Soendergaard, sales agent for GRAS Sound and Vibration (the company that makes my headphone testing tools), told me about this phenomenon and was kind enough to show me a very interesting PDF file describing the development of modern hearing simulators. and simulators of the head and torso.

Scholar SK was very wise and witty. SC Dalsgaard from the University of Odense, which is related to the above-mentioned project - he said: "We model the perception of a person with a very large error."

Coendergard clarified:

"Every minute change in the geometry of the auditory canal (the shape of the auditory canal, the number of folds in the canal, the ratio of its sides, the arrangement of double bends, the size of the eardrum, etc.) affects the auditory perception - especially the perception of high frequencies with very short lengths waves. "

You can see this on the graph above, which is a simplified version of the diagram presented in the PDF file that I mentioned. The graph compares the testimony of 11 subjects received inside the ear canals with the testimony of a device designed to test hearing aids. For each frequency tested, the amplitude-frequency characteristic of the device (solid line), the averaged sound pressure values ​​of 11 test objects (a circle) and the amplitude of the impact (a piece that looks like a broad H letter) can be observed.

As you can see, the sound pressure on the auditory channels at frequencies below 1 kHz does not change much compared to the device, at frequencies above 2 kHz, the differences become larger, and at frequencies above 10 kHz, the difference is simply huge and amounts to + 4 dB. Objectively, the difference of +/- 2 dB, say while lowering the bass by 2 dB and raising the level of high frequencies by 2 dB, is enough to affect the tonal balance of the headphones.

Sendergard and I analyzed the measurement data - we had to conclude that everyone’s hearing is different, because our eardrum is a measuring device, the principle of action of which is similar to a microphone in an aural simulator. As Soandergard said, if you move a person’s eardrum even by a millimeter, a study at frequencies from 10 to 20 kHz (the threshold of hearing of the human ear) will yield completely different results.

Thus, differences in the shape of the ear canal, as well as the fact that people with different ear and ear ear shapes use the headphones, can affect the perception of high-frequency sound. A difference of only 1mm can affect the quiet sound of the headphones and make it either too pronounced or too muffled.

I experienced this from my own experience a few years ago, when the composer (whose name remains unknown) told me that he really liked only the internal channel headphones. These were headphones that sounded incredibly dumb, and most reviewers agreed with this. The measurements I took confirmed the 3 kHz deviations. I collaborated with this person in the past, and we both came to the same conclusions regarding overhead and full-size headphones, but his conclusions regarding in-ear headphones were completely different from mine (later the audiologist said that the shape of his ear canal was extremely unusual).

Everyone’s sense of space is different, at least in headphones

Reason # 2: The transfer function in the brain works differently for everyone.

Your brain uses the transfer function of the head to determine sound in three dimensions. The function takes into account differences in the time it takes for the sound to reach each ear, differences in loudness for each ear, and differences in the amplitude-frequency response caused by the acoustic effect of your head, shoulders and auricles when sound comes from different directions. Your brain processes and interprets all these signals to tell you where the sound source is located.

The use of headphones eliminates the influence of acoustic effects of the body and changes the time of arrival of the signal and its volume in comparison with listening to music through a speaker system or at a live concert. Unfortunately, your brain cannot simply turn off the transfer function. When you put on headphones, your brain continues to try to determine the source of the sound, and cannot do it correctly, as a result there is a feeling that the sound source is right in your head.

I realized that everyone has their own unique transfer function of the head when I visited Virtual Listening Systems in early 1997. To create a headphone processor, which later became known as Sennheiser Lucas , VLS studied the properties of sound perception in hundreds of people. To do this, they put tiny microphones in their ear canals and put them in a soundproof room . A small speaker on the robotic arm reproduced the M-sequence of sounds. The robot moved the speaker to one of 100 different positions, from different angles, each time issuing a series of signals, so that the microphones in the testers' ears could “hear” how the body and the ears influence the sound perception.

(Headphone lovers may notice that this procedure is similar to the measurement method used by Smyth Research and used to create the A8 Realiser processor)

I passed the VLS test on my own. The company's scientists have uploaded my results to a processor that changes the audio signal and makes it identical to the transfer function of the head. The result was amazing, I did not hear that at least one audio processor used by the headphones reproduced something like that. I heard an accurate, perfectly centralized picture, as if the vocalist was right in front of me - even Dolby headphones didn’t have this effect on me.

VLS took readings from hundreds of people and created 16 different presets for the Lucas processor, each of which mimics the transfer function. Turning each of them in turn, it is difficult to dwell on any one. I remember that some of the settings were clearly better than all the others, but it was difficult for me to choose one among the top four or five. But none of them gave the same result as that selected individually for me in the VLS laboratory.

Probably for this reason, most headphone processors have much fewer settings, and they work on some average transfer function. Maybe you are lucky and your transfer function will be close to this approximation. Or not, then the sound will seem to you too saturated, and maybe too weak.

Since each has its own transfer function of the head, just as well, each has a different compensation curve that affects the sound - something like an equalizer. When a characteristic of your body is superimposed on the compensation curve, the result is the sound that you hear daily. If you eliminate the influence of body parameters by using headphones, then your brain will only rely on the compensation curve. And since each of these curves is individual, the effect of the same headphones on different people is different.

No Isolation - No Bass

Reason # 3: The shape of the headphone changes the sound.

Good sound reproduction largely depends on the shape of the headphones. In particular, on how the earpieces of full-size headphones are wrapped around the ears, on-ear headphones on the auricle, or on how conveniently the channel earphone is made of silicone or foam material in the ear. If the headphones have a good sound insulation, then the whole bass that they are able to produce will flow into the ears. If there is a “sound leak” somewhere, the bass will be less pronounced, and you will notice how the tonal balance will shift towards the higher frequencies.

In part, the physical features of your body determine which headphones are right for you. For example, if none of the interchangeable tips of in-ear headphones are suitable for you, then their sound will not seem good to you. This can be a problem for me, because I have an unusually large size of the ear canals, and for my colleague Jeff Morrison (Geoff Morrison), since he has them unusually small. For this reason, I always thank the manufacturers of headphones that put five or more different covers in the box with headphones. So, if you are unhappy with the sound of your in-ear headphones, you may want to take a closer look at the foam pads from Comply.

Poor fit overhead and full-size headphones are also not uncommon. I dare to suggest that this, to a greater extent, concerns the latter, since in order to achieve good noise insulation, many factors must be taken into account. Among such factors can be identified long and / or thick hair, glasses and even earrings in the ears. Take away the ear cushions at least a millimeter from the head, and part of the bass will disappear, which significantly affects the sound quality of the headphones.

Full-size and overhead headphones are suitable for some people better than others. Some headphones for music lovers, such as the Audeze LCD-XC, have so big ear cushions that they can fully embrace the ears and part of the cheek in relatively miniature people, especially women. At the same time, some supposedly full-size headphones are not even capable of covering large earlobes like mine.

It should be noted that poor insulation can have a positive effect. A slightly weakened sound insulation can make the sound of headphones with powerful bass more even - we found this out, creating a review of the “Best in-channel headphones for $ 100” for The Wirecutter. Of the earphones considered in that topic, my favorites are Grain Audio IEHP , which for me produce an excellent smooth and natural sound. I decided that IEHP sounded so good because the silicone covers provide good sound insulation. Although for everyone else, IEHP's bass was too strong. Apparently, the pads did not provide me with proper noise insulation, but provided it to others, and this radically changed my attitude towards headphones for the better.

Reasons that do not depend on headphones

Reason # 4: Personal Preferences

Of course, there are reasons that are applicable not only to headphones, for which people diverge in the perception of sound.

The first reason, it’s the most obvious one: different people have different musical tastes. Some like a little more bass than you, or more treble. Obviously, you will choose different headphones.

In continuation of the topic. In addition to normal, normal taste preferences, some people have an erroneous, or, frankly, wrong opinion about sound. We all met people who believe that a good sound is nothing more than a ridiculously loud bass. Some enthusiasts prefer strongly pronounced high frequencies, which they mistakenly consider accuracy and detail. I myself went through this, but the invaluable works of Gordon Holt (J. Gordon Holt) guided me along the right path.

Whatever makes such listeners happy, it has a right to exist, but their opinions about sound can be useful only for those who have similar extreme tastes, and such people try to justify their choice with unprofessional and unfounded judgments.

Reason # 5: Hearing capabilities change with age, depending on gender or lifestyle.

Although most of us are born with roughly the same hearing possibilities, they change throughout life.

The more you are exposed to loud sounds, the more likely you are to partially lose sensitivity to high frequencies. In particular, this is a problem for people whose leisure time (trips to loud concerts, driving racing cars, hunting, etc.) and / or work (construction, military, manufacturing, etc.) are associated with loud sounds.

The older you get, the more likely you are losing the perception of high frequencies. This is especially true for men. According to the article "Research on gender differences and age-related hearing impairment" from the Journal of the American Acoustical Society: "... the hearing sensitivity of most frequencies decreases more than two times faster in men than in women ..." Partly because men are more likely than women to work, where they are exposed to loud sounds, such as the one mentioned above. Also, studies have shown that men perceive loud sounds much better, 6-10 decibels above the level of sound comfortable for women.

Obviously, the perception of the characteristics of an audio device will change, according to changes in hearing. For example, the curvature of high order harmonics, which occurs at frequencies 5 and more times higher than the fundamental frequency of sound, will obviously disturb the 25-year-old woman more than the 60-year-old elderly man, besides, he may not even hear the sound of 12 kHz. but it will be unbearable for a 25 year old woman.

What can we do about it?

This begs the obvious question: “How can any headphone be evaluated so that it is informative and useful for any listener?”

Unfortunately nothing. But we can try.

In my opinion, the key is to take readings from many listeners with different shapes of heads and ear canals. Lauren Dragan did this in a headphone review organized for The Wirecutter , and we did when I was at Sound & Vision.

I would like to do this here at About.com Stereos, but unfortunately it is not financially profitable to do this, given the small number of headphones I watch and how much I get paid for it. So the best thing I can do is to provide links to my other reviews whenever possible. My articles for About.com Stereos and Headphones for SoundStage! I supplement Xperience with laboratory measurements to give an objective idea of ​​what the amplitude-frequency characteristic of headphones is.

The "gold standard" should take into account the opinion of many students and laboratory measurements. I did this when I was working on Sound & Vision, but at the moment I don’t know a single publication that does this.

One simple rule follows from all this: be careful before making fun of other people's opinions about headphones.



Special thanks to Jacob Soendergard from GRAS Sound and Vibration and Dennis Burger (Dennis Burger) for their help and feedback on the article.