The secret of the ritual “warming up” or why the “warm” headphones sound “better”

    A couple of years ago we already touched on the so-called theme. warming up the headphones . Then we found out that headphone manufacturers consider “warming up” as heresy and have no specifications about “warming up” and declare that it does not change anything. In particular, representatives of Shure and Sennheiser noted that their products are ready for use without additional rituals and do not need prior preparation or adjustment for accurate sound reproduction.

    More than two years have passed since the publication of that post, during which articles from supporters of warming up continued to appear on the net. I decided to further dig the issue and study the impressions of people who tried to feel the effect of warming up. I suggested to my friends who buy headphones to “warm up” them and subjectively compare the fidelity of reproduction before and after the procedure.

    At first I was a little dumbfounded and prepared to write a refutation to the opus of two years ago. The fact is that most of those who set up this experiment noted that “sound quality” became “better”, “increased fidelity of reproduction”. I was interested in this paradox and, as it seems to me, I understood for what reason many felt “changes” after “warming up”.

    Briefly about the “theory” of heating

    For those who are not yet aware of the “theory of warming up,” I will summarize the essence thereof. Not a few people believe that as a result of “warming up”, i.e. long play music or pink noise (from 12 hours or more) headphones, their sound is improved. Believers in the “warm-up” can be divided into several types of denominations , depending on the warm-up time, as well as its methods (music, noise or warm-up cords with special devices).

    “Scientific” justification is also available. It is argued that, like any mechanical system, headphones require running in, lapping, “shrinkage”, “scrap”, “development”. A mole working in a certain mode (for example, when playing pink noise) allows you to “increase the elasticity of the diffuser”. In practice, it is noted that any changes that can occur in the headphones during “warm-up” cannot be detected by ear and are not recorded by measuring instruments (there are no changes in the frequency response, THD, IMD and other significant characteristics).

    Presumably, a similar effect was observed in the old Soviet dynamic loudspeakers (for example, 75GD1), where “warming up” (running at high volume with pink noise for 80 hours) allowed to shift the low-frequency range by 1-1.5 Hz. However, such a change could be caused by changes in temperature, humidity and other external conditions affecting the cellulose cone and it is almost impossible to determine by ear.

    Periodically, a network of videos with measurements of changes in the frequency response after warming up, for example, this:

    The first thing that attracts attention is the insignificance of changes in the frequency response, and the second complete lack of information about the measurement conditions.

    My observations

    It is hardly possible to consider collecting the impressions of several of my acquaintances as a full-fledged study, but due to the absence of others with any kind of reliable data on this issue, it is necessary to rely on what is.

    In total, 42 people took part in this handicraft similarity of the experiment in 2 years. They used 18 different models of headphones from 10 manufacturers. Of these, the vast majority used in-ear headphones - 33 people (29 - dynamic, 4 - reinforcing), 6 full-size people (5 dynamic, 1 isodynamic) and 4 people overhead (all dynamic).

    34 respondents used the so-called. “Warming up” with music, i.e. they played music, 8 used “warming up” with pink noise. I asked to warm up for 48 hours, because from the adepts of “warming up” one often hears that such a duration is effective.

    At first glance, testimonials testified that there is a powerful subjective effect on “warming up”. 37 people out of 42 said that after a 48-hour “warm-up” they felt a noticeable improvement or change in sound. Of course, this was perceived by me as a paradox, because even 80 hours of “warming up” of a large woofer are not capable of somehow significantly affecting its properties and measurement results.

    Hypothesis and blind test

    I decided to interview the respondents in more detail and clarify exactly which improvements they noticed. It turned out that even people with the same headphone models reported completely different changes. For example, 3 people immediately acquired, on my recommendation, the same model of full-size Marshall headphones and got completely different effects from “warming up”, although all three performed the same actions.

    So one claimed that the sound of the headphones became more “voluminous” and “musical”, the second spoke about the improvements in the low-frequency range - “the bass became deeper and more pronounced.” The third one found out that thanks to the “warming up”, the “scene opened up” in the mid frequencies and midbass. Similarly, other interviewees assessed changes in sound in completely different ways. Overwhelmingly, people just talked about improvement.

    I was not able to identify any correlations between the model, type of construction or emitter, the manufacturer and the features of the described changes. These were completely different estimates for different models. Thus, I came to the conclusion that it was not warming up, but especially perception. Initially, I suspected a banal placebo effect, thinking that my proposal itself suggested to the respondents that there should be any positive changes after the “warm-up”.

    However, later I began to ask people who do not “warm up” the headphones, but use them for a long time. And, it seems to me, reliably determined where the very subjective effect comes from. Those who did not warm up the headphones also reported that some time after using new headphones, they noticed positive changes. I suggested that the whole thing is in adapting the hearing to the frequency response, distortion and other features of the sound. Probably, the brain eventually got used to the characteristic features of reproduction, and the sound began to be perceived differently.

    I was able to make sure that my assumptions were correct when I suggested that my friends conduct a series of blind tests.and compare the “heated” headphones with similar unheated. The result turned out to be predictable: out of four people who tried to identify heated headphones among two identical models, not one could go beyond the limits of random guessing. Moreover, they all noted that they did not find differences in sound between “heated” and “cold” headphones.

    Natural result

    I am convinced that the adaptation effect of the auditory perception is the only reason for the differences in the subjective assessment of the quality of reproduction on “heated” and “unheated” headphones. This is confirmed by the fact that no one has yet reliably recorded any significant changes in the sound due to “warming up”. The warming myth is successfully used in marketing, since a consumer who is not subjectively satisfied with the sound of headphones can be offered to “warm up” them, i.e. actually wait until his brain gets used to the features of the sound. Some time ago even discs with pink noise for heating headphones were sold, then they began to be distributed free of charge.

    We sell headphones , different, a lot.

    The opinion of the author of the material is not the official position of the company PULT.RU, which in matters of "warming up" retains neutrality, based on an insufficient study of the issue in acoustics and physics of a solid body.

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