如何去看待哈曼曲线？Where Are We At With The Harman Curve?
转一篇最近的新闻（12月1日），大家理性探讨。
It's hard for me to believe it's been seven years since researchers from Harman International presented the landmark paper “The Relationship between Perception and Measurement of Headphone Sound Quality” at the 2012 Audio Engineering Society Convention in San Francisco -- the first paper in which the company presented what became known as the “Harman Curve,” the target frequency response that average listeners would like best. When I first read that paper, I assumed it would quickly revolutionize the headphone business. As a headphone reviewer, I knew that the various headphones and earphones then on the market often exhibited wildly different sounds -- even among different models in a company’s line -- which indicated that knowledge was lacking or simply being ignored.
Yet we didn’t see a surge in headphones claiming to use the Harman Curve -- not even from Harman companies AKG, JBL, and Harman Kardon, although other manufacturers had quietly confided to me that they were basing theirdesigns on the Harman Curve. In fact, the first set of passive headphones I’ve received from a Harman company using the Harman Curve only came across my desk last month: the AKG K371s-- and the only way I knew that they were voiced within 1dB of the Harman Curve was by reading a Facebook post from Harman senior fellow Sean Olive.
It looks, though, like the dam is finally bursting. In a presentation last month to the Los Angeles chapter of the AES, Olive highlighted several other headphones and earphones designed along the lines of the Harman Curve (although not, as best I can tell, marketed as such). The earphones include Samsung Galaxy Buds; JBL Live 200s, Live 500s, Live 650s, and Reflect Flows; and AKG N5005s. Headphones, for now, seem to include only the AKG N700 NCs, K371s and K361s, but we can expect more. As Olive told me later in an e-mail, “Basically all new AKG headphones are designed to Harman target and for the past year JBL has followed it but with 2dB extra bass below 125Hz.”
Olive’s presentation detailed Harman’s ambitious research into headphones, which has since 2012 resulted in 19 papers, one patent (and three more pending), and a one-click routine for the SoundCheck audio measurement suite that uses the Harman Curve to predict listener preference. The effort started with the realization that, as Olive put it, “There were standards for diffuse-field and free-field headphone response, but no one was following them so there must have been something wrong.
“At the time, our marketing department was telling us that we should duplicate the response of Beats headphones, because those were the best-sellers,” he continued. But Harman’s researchers had already evaluated those headphones in blind tests, and found them to be unpopular among their listeners. “So we told them they should duplicate Beats’ marketing instead,” he said.
The researchers’ idea was that if headphone designers knew what measured response best suited the largest number of listeners, the designers could then tailor their products’ frequency responses to that target. This would be more efficient than “shooting in the dark” by building headphones, putting them through listening tests (which, if you want them to be blind, are much more complicated with headphones than they are with speakers), then repeating the process until most of the listeners are pleased.
Harman’s first effort involved a blind test of six over-ear headphones, followed by measurements of those response curves to see what response pleased the most listeners. Subsequent projects solicited the judgment of hundreds of listeners around the world, and measurements of hundreds of different headphones.
The result of all that effort was Harman Curves for earphones and over-ear headphones. But as Olive suggested in his above comment about JBL headphones, it’s not a “one-size-fits-all” target. His presentation identified three potential groups to which manufacturers can target their headphones.
“Harman Curve Lovers”: This group, which constitutes 64% of listeners, includes mostly a broad spectrum of people, although generally under age 50. They prefer headphones tuned close to the Harman Curve.
“More Bass Is Better”: This next group, which makes up 15% of listeners, prefers headphones with 3 to 6dB more bass than Harman Curve below 300Hz, and 1dB more output above 1kHz. This group is predominantly male and younger -- the listeners JBL is targeting with its headphones.
“Less Bass Is Better”: This group, 21% of listeners, prefers 2 to 3dB less bass than the Harman Curve and 1dB more output above 1kHz. This group is disproportionately female and older than 50.
According to Olive, his group still has some more research into headphones to do, but they’re starting to wrap it up and anticipate moving on to new projects. We don’t yet have enough information to know if the Harman Curve will result in greater sales, millions more happy listeners, and Better standardization of headphone evaluation. I’ve learned from listening to several headphones and earphones that come close to the Harman Curve that it is, at the very least, an excellent baseline for performance. Headphones and earphones may, for various reasons, deviate to some extent from the Harman Curve. But if their measured response is far from the Harman targets, listeners and reviewers should at least question why, and the manufacturer should be able to respond with a plausible rationale based on research and testing.
I expect we’ll encounter manufacturers and reviewers who simply claim, “I listened to some Harman Curve headphones and I don’t think they sound very good.” Audio enthusiasts will then have to decide if they trust the conclusion of a single person, determined through casual, sighted testing, or the conclusion of years’ worth of research conducted with hundreds of listeners in carefully controlled blind tests. I know which way I’ll go.
. . . Brent Butterworth
brentb@soundstagenetwork.com
我很难相信，自从哈曼国际的研究人员在2012年旧金山国际音频工程协会会议上发表了具有里程碑意义的论文“耳机音质的感知和测量之间的关系”以来，已经有七年了，这是哈曼国际在第一篇论文中提出的所谓“哈曼曲线”，听众平均最喜欢的目标频率响应。当我第一次读到那篇论文时，我以为它会很快给耳机行业带来革命性的变化。作为一名耳机评论员，我知道当时市面上的各种不同型号的耳机经常表现出迥然不同的声音——即使是在一家公司生产的不同型号之间——这表明缺乏相关知识，或者只是被简单的忽视了。
然而，我们并没有看到声称使用哈曼曲线的耳机激增——甚至哈曼国际自己的AKG、JBL和Harman/Kardon也没有，尽管其他制造商已经悄悄地向我透露，他们正在设计基于哈曼曲线的耳机。事实上，上个月，第一批我从哈曼国际收到的使用哈曼曲线的被动耳机才出现在我的办公桌上：AKG K371——我知道它们在哈曼曲线±1dB范围内的唯一方式就是阅读哈曼国际高级研究员Sean Olive在Facebook的帖子。
不过，看起来大坝终于要决堤了。在上个月向AES洛杉矶分部的一次演示中，Olive着重介绍了其他几款按照哈曼曲线设计的耳机(尽管据我所知，它们并不是按照哈曼曲线设计的)。包括三星Galaxy Buds; JBL Live 200，Live 500，Live 650，Reflect Flow；和AKG N5005。目前，这些耳机似乎只包括AKG N700 NC, K371和K361，但我们可以期待更多。正如Olive后来在一封电子邮件中告诉我的，“基本上所有新设计的AKG耳机都是按照哈曼目标曲线设计的，在过去的一年里JBL也遵循了这一标准，但额外在125Hz以下增加了2dB的低音。
这里我要更正一下，至少我测试过的，N5005和Galaxy Buds是哈曼曲线耳机，也许作者没有搞清楚。。。
Olive的演讲详细介绍了哈曼对耳机的雄心勃勃的研究，自2012年以来，哈曼国际对耳机研究发表了19篇论文、1项专利（还有3项正在申请中）和SoundCheck audio measurement suite的一键式程序，该程序使用哈曼曲线来预测听众的偏好。正如Olive所说，这项工作的开始是意识到“有扩散场和自由场耳机响应的标准，但没有人遵循这些标准，所以肯定是哪里出错了。 ”
“当时，我们的市场部告诉我们，我们应该复制Beats耳机的频响，因为它们是最畅销的，”他继续说。但哈曼的研究人员已经在盲测中评估了这些耳机，发现它们在听众中不受欢迎。他说：“所以我们告诉他们应该复制Beats的营销模式。 ”
哈曼研究人员的想法是，如果耳机设计师知道什么样的测量响应最适合最大数量的听众，那么设计师就可以根据这个目标定制他们产品的频率响应。这将比“盲人摸象”的方法研发耳机更有效。让他们通过听力测试（如果你想让人们盲听，戴耳机要比听扬声器复杂得多），然后重复这个过程，直到大多数听众满意为止。
哈曼国际的第一项研究是对六个入耳式耳机进行盲听，然后测量这些耳机的响应曲线，看看最让听众满意的是什么。随后征求了全世界数百名听众的意见，并测量了数百种不同的耳机。
所有这些努力的结果就是耳机的哈曼曲线。但正如Olive在上述关于JBL耳机的评论中所暗示的，这并不是一个“一刀切”的目标曲线。他的演讲中确定了三个潜在的群体，制造商可以瞄准他们设计耳机。
“哈曼曲线爱好者”：这一群体占听众的64%，其中大部分人都是广泛分布的，尽管一般都在50岁以下。他们更喜欢在哈曼曲线附近调音的耳机。
“低音越多越好”：占听众15%的下一组人更喜欢低音比300赫兹以下的哈曼曲线多3至6dB的耳机，耳机在1kHz以上也多1dB。这一群体主要是男性和年轻人——JBL耳机所瞄准的这部分听众。
“低音越少越好”：21%的听众喜欢比哈曼曲线少2到3分贝的低音，高于1kHz多1dB。这个群体中女性和年龄超过50岁的长者比重较高。
据Olive所说，他的团队还需要对耳机做更多的研究，但他们已经开始总结，并预计将继续进行新的项目。我们还没有足够的信息来知道哈曼曲线是否会带来更大的销量，使数百万听众快乐，以及更好的耳机评价标准化。我从听几款接近哈曼曲线的耳机中了解到，它至少是一个出色的基础。由于各种原因，耳机和耳机可能会在一定程度上偏离哈曼曲线。但如果他们的测量结果与哈曼的目标相距甚远，那么听众和评论者至少应该质疑其原因，制造商应该能够根据研究和测试给出合理的解释。
我能预料到我们会遇到一些制造商和评测人员，他们只是声称，“我听了一些哈曼曲线耳机，我觉得它们听起来不太好。”然后，音频发烧友将不得不决定他们是否相信一个人通过随意的非盲听测试确定的结论，还是多年来对数百名听众在精心控制的盲听实验中进行的研究得出的结论。我知道我会走哪条路。
基于哈曼曲线的耳机预测评分属于心理声学预测模型，而这种模型 是有一定的误差和浮动范围的。我过去的测评基本上都是主客观评价，算法评分通常都会标准仅供参考。主客观评价是声学行业内最普遍的一种做法，但我感觉即便整整一年过去了，还是有很多人不太了解，所以近期会专门写一篇相关的介绍。
