Much of Western classical music uses instruments based on acoustic resonance. Such instruments produce harmonic or quasi-harmonic sounds. On the other hand, since the early 1970s, popular music has largely been produced in the recording studio. As a result, popular music is not bound to be based on harmonic or quasi-harmonic sounds. In this study, we use modified MPEG-7 features to explore and characterise the way in which the use of noise and inharmonicity has evolved in popular music since 1961. We set this evolution in the context of other broad categories of music, including Western classical piano music, Western classical orchestral music, and musique concr\`ete. We propose new features that allow us to distinguish between inharmonicity resulting from noise and inharmonicity resulting from interactions between relatively discrete partials. When the history of contemporary popular music is viewed through the lens of these new features, we find that the period since 1961 can be divided into three phases. From 1961 to 1972, there was a steady increase in inharmonicity but no significant increase in noise. From 1972 to 1986, both inharmonicity and noise increased. Then, since 1986, there has been a steady decrease in both inharmonicity and noise to today's popular music which is significantly less noisy but more inharmonic than the music of the sixties. We relate these observed trends to the development of music production practice over the period and illustrate them with focused analyses of certain key artists and tracks.

翻译：西方古典音乐大多采用基于声学共振原理的乐器，这类乐器产生谐波或准谐波声音。然而自20世纪70年代初以来，流行音乐主要在录音室中制作，因此不必受限于谐波或准谐波声源。本研究采用改进的MPEG-7特征，探索并刻画了1961年以来流行音乐中噪声与非谐和性运用的演变轨迹。我们将这种演变置于更广阔的音乐类别背景下进行考察，包括西方古典钢琴音乐、西方古典管弦乐以及具体音乐。本文提出了能够区分噪声引起的非谐和性与离散分音相互作用引起的非谐和性的新特征。通过这些新特征审视当代流行音乐的发展历程，我们发现1961年至今可分为三个阶段：1961-1972年间非谐和性持续增长而噪声未显著增加；1972-1986年间非谐和性与噪声同步增长；1986年至今两者持续下降，当前流行音乐虽比六十年代音乐更具非谐和性，但噪声水平显著降低。我们将这些观测趋势与该时期音乐制作实践的发展相联系，并通过重点分析代表性艺术家与作品加以阐释。