总体来说，人们应该更喜欢和平宁静而不喜欢噪音——这种想法貌似有些道理。我们大多数人都有过这样的经历：如果在深山或者乡村睡觉，必须作一些调整才能睡得着，因为这些地方起初“太安静”了。这一例子说明人类有能力去适应不同程度、分贝跨度较大的各种噪音。研究也证实了这一点。例如，Glass和 Singer(1972)将人们置于瞬间发出的非常刺耳的噪声环境之中。然后测量他们解决问题的能力和由此产生的生理反应。起初，噪音让人心烦意乱。但大约四分钟后，将置于噪音下的实验对象与处于正常环境中的人们相比发现，前者在完成任务方面做得很不错，而且他们对噪音的生理反应也会迅速降低到与后者持平的水平。

In general, it is plausible to suppose that we should prefer peace and quiet to noise. And yet most of us have had the experience of having to adjust to sleeping in the mountains or the countryside because it was initially `too quiet', an experience that suggests that humans are capable of adapting to a wide range of noise levels. Research supports this view. For example, Glass and Singer (1972) exposed people to short bursts of very loud noise and then measured their ability to work out problems and their physiological reactions to the noise. The noise was quite disruptive at first, but after about four minutes the subjects were doing just as well on their tasks as control subjects who were not exposed to noise. Their physiological arousal also declined quickly to the same levels as those of the control subjects.

但如果要求试验对象同时专注几项任务时，其对噪音的适应性能力就会达到极限，噪音也会变得更加让人心烦意乱。例如，如果一个实验对象需要同时监视三个刻度盘，那么高分贝噪音就会严重干扰他们完成工作。同时监视多个刻度盘其实和飞行员或者空中交通调解员的工作别无二致(Bmadbent，1957)。同理，噪音并不会影响实验对象追踪一个旋转轮子形成的不断移动的轨迹，但如果让实验对象在追踪的同时重复数字，那么噪音对他们的影响就很大了(Finkelman and Glass, 1970)。

或许，此项关于噪音的研究最重大的发现，就是噪音的可预见性要比它分贝的大小更为重要。我们完全有能力对长期存在的背景噪音“听而不闻”，即使它们确实很吵：而如果人们工作时受到突如其来的噪音的侵袭，他们就会很不适应。在Glass和Singer的研究中，当实验对象正做一项工作时，把他们置于突然发出的噪音环境中，有些人听到的声音非常大，而有些人听到的声音却要柔和得多。实验对象中一部分人听到的噪音是严格按照一分钟的时间间隔产生的(可预测性噪音)；其他人听到的噪音总量是不变的，但是产生时间却是随机的(非可预测性噪音)。实验组称，可预测性噪音和非可预测性噪音都很恼人，而所有实验对象在噪音测试部分的表现都处在同一水平线上。然而，在无噪音环境下要求实验对象校对书面材料时，不同噪音条件带来的副作用是迥然不同的。如表1所示，和可预测性噪音相比，非可预测性噪音使试验对象在校对时出现更多错误；柔和的非可预测性噪音实际上比吵闹的可预测性噪音让人出现更多错误。

But there are limits to adaptation and loud noise becomes more troublesome if the person is required to concentrate on more than one task. For example, high noise levels interfered with the performance of subjects who were required to monitor three dials at a time, a task not unlike that of an aeroplane pilot or an air-traffic controller (Broadbent, 1957). Similarly, noise did not affect a subject's ability to track a moving line with a steering wheel, but it did interfere with the subject's ability to repeat numbers while tracking (Finkelman and Glass, 1970).

表格1：校对错误与噪音

Probably the most significant finding from research on noise is that its predictability is more important than how loud it is. We are much more able to 'tune out' chronic background noise, even if it is quite loud, than to work under circumstances with unexpected intrusions of noise. In the Glass and Singer study, in which subjects were exposed to bursts of noise as they worked on a task, some subjects heard loud bursts and others heard soft bursts. For some subjects, the bursts were spaced exactly one minute apart (predictable noise); others heard the same amount of noise overall, but the bursts occurred at random intervals (unpredictable noise). Subjects reported finding the predictable and unpredictable noise equally annoying, and all subjects performed at about the same level during the noise portion of the experiment. But the different noise conditions had quite different after-effects when the subjects were required to proofread written material under conditions of no noise. As shown in Table 1 the unpredictable noise produced more errors in the later proofreading task than predictable noise; and soft, unpredictable noise actually produced slightly more errors on this task than the loud, predictable noise.

显然，非可预测性噪音会让人更疲劳，不过疲劳导致工作上的错误还需要一段时间。

预测性不是唯一可以减少或着消除噪音负而影响的变量。另一个变量是噪音的可控性。如果一个人知道自己可以控制噪音的话，这一点似乎可以消除当时噪音的负面影响和副作用。即使人们没有真正实践他的想法，去关掉噪音，这种效果也是可以达到的。仅知道自己有控制噪音的能力就足够了。

到目前为止，所讨论的研究都是将人们短时间置于噪音环境中，也只是研究了由此带来的瞬间影响。但是噪音环境所引起的主要忧虑是，日复一日地长期生活在噪音环境中可能会产生严重、持久的影响。一项研究表明，此担心是有现实性的。将在洛杉矶最繁忙的机场旁边上学的小学生和那些在安静环境中上学的小学生相比较(Cohen et al., 1980)，就会发现噪音地区的小学生血压较高，更容易转移注意力。此外，并没有迹象表明孩子们会逐渐适应噪音。事实上，孩子们在喧闹的学校待的时间越久，他们越难以集中注意力。另外一项跟踪研究表明，和那些一直在安静学校上学的孩子相比，即使喧闹学校里的孩子们搬到安静一些的学校待上一年以后，他们还是难以集中注意力。有一点需要说明的是，两组孩子都是经过研究人员精心匹配的，他们在年龄、民族习性、种族和社会阶层上都具有可比性。

Table 1: Proofreading Errors and Noise

Apparently, unpredictable noise produces more fatigue than predictable noise, but it takes a while for this fatigue to take its toll on performance.

Predictability is not the only variable that reduces or eliminates the negative effects of noise. Another is control. If the individual knows that he or she can control the noise, this seems to eliminate both its negative effects at the time and its after-effects. This is true even if the individual never actually exercises his or her option to turn the noise off (Glass and Singer, 1972). Just the knowledge that one has control is sufficient.

The studies discussed so far exposed people to noise for only short periods and only transient effects were studied. But the major worry about noisy environments is that living day after day with chronic noise may produce serious, lasting effects. One study, suggesting that this worry is a realistic one, compared elementary school pupils who attended schools near Los Angeles's busiest airport with students who attended schools in quiet neighbourhoods (Cohen et al., 1980). It was found that children from the noisy schools had higher blood pressure and were more easily distracted than those who attended the quiet schools. Moreover, there was no evidence of adaptability to the noise. In fact, the longer the children had attended the noisy schools, the more distractible they became. The effects also seem to be long lasting. A follow-up study showed that children who were moved to less noisy classrooms still showed greater distractibility one year later than students who had always been in the quiet schools (Cohen et al, 1981). It should be noted that the two groups of children had been carefully matched by the investigators so that they were comparable in age, ethnicity, race, and social class.