Have you ever wondered why certain pop songs just make you feel so good?
你可曾好奇过为什么某些流行歌曲会让你感觉这么愉快？
Researchers studying the question found that the right combination of uncertainty and surprise is what gives listeners the most pleasure.
研究人员发现，恰到好处地融合不确定和惊奇因素是让倾听者感到愉悦的原因。
The study, published in the journal Current Biology, involved an analysis of 80,000 chords in 745 pop songs from the US Billboard "Hot 100" chart between 1958 and 1991.
发表在《当代生物学》期刊上的这项研究分析了1958年到1991年间美国公告牌百强单曲榜上的745首流行歌曲中的8万组和弦。
The researchers -- from institutes in Germany, Norway, Denmark and the UK -- used a machine-learning model to quantify the level of uncertainty and surprise of these chords, and then asked 39 adult volunteers to rate how pleasurable they found each series of chords.
来自德国、挪威、丹麦和英国科研机构的研究人员用一种机器学习模型把这些和弦中的不确定和惊奇因素量化了，并请39名成年志愿者给每组和弦带来的愉悦程度打分。
Each song was stripped of its melody and lyrics so that only chord progressions were left and the results couldn't be skewed by other associations to the songs that listeners might have had.
每首歌都去掉了旋律和歌词，只留下和弦进行曲式，这样结果便不会因为歌曲其他元素可能给听众造成的影响而偏离。
They found two things: that participants derived greater pleasure when they were relatively certain what would happen next but then were surprised by an unexpected chord progression.
研究人员发现了两件事。第一，参与者在比较确定接下来要出现的和弦却听到意外的和弦进行曲式时会有更大的愉悦感。
However, the same number of participants found it pleasant when they were uncertain as to what would follow, and then the subsequent chords were more familiar to them.
然而，同样数量的参与者表示，当他们不确定接下来要出现的和弦，却听到了比较熟悉的和弦曲式，也会感到愉悦。
"It is fascinating that humans can derive pleasure from a piece of music just by how sounds are ordered over time," Vincent Cheung, the lead researcher on the paper from the Max Planck Institute for Human Cognitive and Brain Sciences, Germany, said in a statement.
该研究的首席研究员、来自德国马克斯普朗克人类认知与脑科学研究所的文森特·张在一份声明中说：“令人着迷的是，人类仅凭声音的组合顺序就可以从一首乐曲中得到快感。”

"Songs that we find pleasant are likely those which strike a good balance between knowing what is going to happen next and surprising us with something we did not expect. Understanding how music activates our pleasure system in the brain could explain why listening to music might help us feel better when we are feeling blue."
“让我们感觉愉快的歌曲通常是那些在预期接下来会听到的和弦和意外听到的和弦之间保持巧妙平衡的歌曲。理解音乐如何激活我们大脑中的快乐系统可以解释，为什么听音乐可以在我们情绪低落时让我们感觉好起来。”
Cheung told CNN that pleasure in music is linked to expectancy. Previous studies had looked into the effects of surprise on pleasure, but he and his colleagues' study also focused on the uncertainty of listeners' predictions.
张研究员告诉CNN说，音乐带来的愉悦感和预期有关。先前的研究调查了惊奇对愉悦感的效果，但他和同事的研究还关注了听众预期的不确定性。
The songs used in the experiments included James Taylor's "Country Roads," UB40's "Red, Red Wine" and The Beatles' "Ob-La-Di, Ob-La-Da."
用于实验的歌曲包括詹姆斯·泰勒的《Country Roads》、UB40乐队的《Red, Red Wine》和甲壳虫乐队的《Ob-La-Di, Ob-La-Da》。
The findings may help improve artificial musical algorithms and could help composers write music or predict musical trends.
研究结果可能有助于改进人工音乐算法，帮助作曲家编曲或预测音乐潮流。
"The idea is that hopefully as a scientist analyzing these patterns of pleasure in humans, you can somehow work out where music can go next," Peter Harrison, a researcher at Queen Mary University, London, who worked on the project, told CNN.
参与该项目的伦敦玛丽女王大学的研究员皮特·哈瑞森告诉CNN说：“我们希望，科学家通过分析人类的快乐模式可以预期音乐的走向。”
As part of the same experiment, the researchers also used brain imaging to locate the areas of the brain reflected in musical pleasure.
作为实验的一部分，研究人员还用脑成像技术锁定了产生音乐愉悦感的大脑区域。
They found the regions involved were the amygdala, the hippocampus and the auditory cortex, which process emotions, learning and memory, and sound, respectively.
他们发现，这些相关大脑区域是杏仁核、海马体和听觉皮层，它们分别处理情绪、学习和记忆、声音。
Cheung added that another part of the brain, the nucleus accumbens -- which processes reward expectations -- was perhaps responsible for "directing our attention towards the music so that we will try to find out what will happen next."
张研究员补充道，大脑的另一个处理奖励期望的部位——伏核——也许是“将我们的注意力引向音乐”的组织，“这样我们就会试着去弄清楚接下来会发生什么”。