Pop songs have become angrier and sadder over the past 60 years, experts say.
专家表示，在过去60年里，流行歌曲变得越来越愤怒和悲伤。
Researchers analyzed lyrics in best-selling songs from the 1950s to 2016 to find expressions of anger and sadness had increased, while words about joy had dropped.
研究人员分析了上世纪50年代至2016年畅销歌曲的歌词，发现表达愤怒和悲伤的歌词增加了，而表达快乐的歌词减少了。
The US study team looked at lyrics of more than 6,000 songs from Billboard Hot 100 in each year.
美国研究小组对每年登上“公告牌百强单曲榜”的六千多首歌曲的歌词进行了研究。
These are the most popular songs in the US each year as chosen by music fans.
这些歌曲都是由音乐粉丝们推选出来的美国年度最受欢迎歌曲。
In the past songs were ranked mainly by record sales, radio and jukebox plays, but more recently it is based on other popularity indicators such as streaming and social media to reflect changes in music consumption.
过去，歌曲的排名主要看唱片销量、电台和点唱机播放量，但近来的排名是基于其他受欢迎程度指标，比如流媒体和社交媒体播放量，以反映音乐消费的变化。
Tones expressed in each song were analyzed using 'automatic quantitative sentiment' which looked at each word or phrase in the song with a set of tones they express.
研究人员使用“自动量化情绪”对每首歌中表达的语气进行了分析。“自动量化情绪”用一组语气来分析歌曲中的每个单词或词组。
The combination of the tones expressed by all words and phrases of the lyrics determines the sentiment of that song.
歌词中的所有单词和词组所表达的语气结合在一起，就决定了这首歌的情绪。
The sentiments of all Billboard Hot 100 songs in each year are averaged and the average of each year measured whether the expression of that sentiment increased, decreased or remained the same.
研究人员将每年“公告牌百强单曲榜”上的全部歌曲表达的各种情绪进行平均，根据每年的平均值来衡量某种情绪的表达是增加了、减少了还是保持不变。
The analysis showed the expression of anger in popular music lyrics has increased gradually over time.
分析表明，随着时间的推移，流行音乐歌词中愤怒的表达逐渐增加。
Study co-author Lior Shamir, of Lawrence Technological University in Michigan, said: 'The change in lyrics sentiments does not necessarily reflect what the musicians and songwriters wanted to express, but is more related to what music consumers wanted to listen to in each year.'
研究报告的作者之一、密歇根劳伦斯理工大学的利奥尔·沙米尔说：“歌词情绪的变化未必反映了音乐人和词作者想要表达的内容，而更多的是与音乐消费者每年想听什么有关。”
Songs released during the mid 1950s were the least angry and the anger expressed in lyrics has increased gradually until peaking in 2015.
上世纪50年代中期发布的歌曲是最不愤怒的，此后歌词表达的愤怒逐渐增加，2015年达到顶峰。
In the mid 1990s, songs became angrier and the increase in anger was sharper during that time in comparison to previous years.
在上世纪90年代中期，歌曲变得更加愤怒，而且与之前的一些年相比，愤怒情绪增加的程度更明显。
The expression of sadness, disgust and fear also increased over time, although the increase was milder compared to the increase in the expression of anger.
表达悲伤、反感和恐惧的歌词随着时间的推移也逐渐增加，但增加的程度不及表达愤怒的歌词。
Disgust increased gradually, but was lower in the early 1980s and higher in the mid and late 1990s.
表达反感情绪的歌词逐渐增加，在上世纪80年代早期增加的速度缓慢，在90年代中后期增加速度变快。
Popular music lyrics expressed more fear during the mid 1980s and the fear decreased sharply in 1988.
在上世纪80年代中期，流行歌曲歌词表达出更多的恐惧情绪，在1988年这种恐惧情绪的表达快速下滑。
Another sharp increase in fear was observed in 1998 and 1999, with a sharp decrease in 2000.
另一次恐惧情绪的快速增长出现在1998年至1999年，继而在2000年快速下滑。

The study also showed that joy was a dominant tone in popular music lyrics during the late 1950s, but it decreased over time and became much milder in the recent years.
研究还发现，在上世纪50年代晚期，快乐是流行音乐歌词的主旋律，但随着时间的流逝，快乐的歌词越来越少，近年来表现趋平。
An exception was observed in the mid 1970s, when joy expressed in lyrics increased sharply.
而上世纪70年代中期是个例外，歌词中的快乐情绪迅速上升。
The study shows that the tones expressed in popular music change over time and the change is gradual and consistent, with a few exceptions.
研究发现，流行歌曲表达的情绪随着时间的变化而改变，这种改变是渐进和连贯的，其中偶有例外。
Since the researchers analyzed the most popular songs in each year, the study does not show that music changed, but that the preferences of music consumers have changed over time.
研究人员分析了每年的最流行歌曲，研究并未表明音乐在改变，而是音乐消费的偏好随着时间而改变。
While music fans preferred joyful songs during the 1950s, modern music consumers are more interested in songs that express sadness or anger.
上世纪50年代的乐迷偏爱欢快的歌曲，而现代音乐消费者对表达悲伤或愤怒的歌曲更感兴趣。
The findings appear in the Journal of Popular Music Studies.
这一发现发表在《流行音乐研究杂志》上。