The shift from silent to sound film at the end of the 1920s marks, so far, the most important transformation in motion picture history. Despite all the highly visible technological developments in theatrical and home delivery of the moving image that have occurred over the decades since then, no single innovation has come close to being regarded as a similar kind of watershed. In nearly every language, however the words are phrased, the most basic division in cinema history lies between films that are mute and films that speak.

Yet this most fundamental standard of historical periodization conceals a host of paradoxes. Nearly every movie theater, however modest, had a piano or organ to provide musical accompaniment to silent pictures. In many instances, spectators in the era before recorded sound experienced elaborate aural presentations alongside movies' visual images, from the Japanese benshi (narrators) crafting multivoiced dialogue narratives to original musical compositions performed by symphony-size orchestras in Europe and the United States. In Berlin, for the premiere performance outside the Soviet Union of The Battleship Potemkin, film director Sergei Eisenstein worked with Austrian composer Edmund Meisel (1874-1930) on a musical score matching sound to image; the Berlin screenings with live music helped to bring the film its wide international fame.

Beyond that, the triumph of recorded sound has overshadowed the rich diversity of technological and aesthetic experiments with the visual image that were going forward simultaneously in the 1920s. New color processes, larger or differently shaped screen sizes, multiple-screen projections, even television, were among the developments invented or tried out during the period, sometimes with startling success. The high costs of converting to sound and the early limitations of sound technology were among the factors that suppressed innovations or retarded advancement in these other areas. The introduction of new screen formats was put off for a quarter century, and color, though utilized over the next two decades for special productions, also did not become a norm until the 1950s.

Though it may be difficult to imagine from a later perspective, a strain of critical opinion in the 1920s predicted that sound film would be a technical novelty that would soon fade from sight, just as had many previous attempts, dating well back before the First World War, to link images with recorded sound. These critics were making a common assumption—that the technological inadequacies of earlier efforts (poor synchronization, weak sound amplification, fragile sound recordings) would invariably occur again. To be sure, their evaluation of the technical flaws in 1920s sound experiments was not so far off the mark, yet they neglected to take into account important new forces in the motion picture field that, in a sense, would not take no for an answer.

These forces were the rapidly expanding electronics and telecommunications companies that were developing and linking telephone and wireless technologies in the 1920s. In the United States, they included such firms as American Telephone and Telegraph, General Electric, and Westinghouse. They were interested in all forms of sound technology and all potential avenues for commercial exploitation. Their competition and collaboration were creating the broadcasting industry in the United States, beginning with the introduction of commercial radio programming in the early 1920s. With financial assets considerably greater than those in the motion picture industry, and perhaps a wider vision of the relationships among entertainment and communications media, they revitalized research into recording sound for motion pictures.

In 1929 the United States motion picture industry released more than 300 sound films—a rough figure, since a number were silent films with music tracks, or films prepared in dual versions, to take account of the many cinemas not yet wired for sound. At the production level, in the United States the conversion was virtually complete by 1930. In Europe it took a little longer, mainly because there were more small producers for whom the costs of sound were prohibitive, and in other parts of the world problems with rights or access to equipment delayed the shift to sound production for a few more years (though cinemas in major cities may have been wired in order to play foreign sound films). The triumph of sound cinema was swift, complete, and enormously popular.

1920年代末见证了电影史上最重大的一次过渡——电影从无声到有声的跨越。尽管在戏剧和家庭移动影像的传输方面的高级视觉技术在此之前已经发展了数十年，却依然没有哪项革新可以像这项技术一样成为分水岭。几乎所有语言都是这样描述的（尽管措辞略有出入）：电影史上最基本的分水岭就是从默片到有声电影的过渡。

然而这一历史分期的基本标准下依然矛盾重重。几乎每家剧院都配备钢琴或管风琴为无声电影配乐，尽管不起眼。在一些实例中，录音时代之前的观众都有亲身体验，电影放映时旁边是精妙绝伦的音效呈现，从绝妙的日本benshi(口技)多音效对话演绎到欧美管弦交响乐队演奏的原创曲目。为了首次在柏林露天公演前苏联战舰波将金号，该片导演Sergei Eisenstein与奥地利作曲家Edmund Meisel（1874-1930）合作为电影配乐；柏林的电影荧幕配上现场音乐使得这一影片在国际上赢得广泛赞誉。
除此之外，录音的辉煌还使得1920年代同时发展的视觉影像技术和审美体验的成就相形见绌。在这期间新技术新发明层出不穷，有一些技术非常成功：新的色彩处理，更大以及不同形状的屏幕尺寸，多屏放映的设计，甚至是电视机的出现。声音转化的高成本和早期声音技术的局限阻碍了这些发明在其所在其他领域的发展。25年之后新型屏幕设计才得以引进，并且尽管色彩在接下来的20年中都用于专业生产，但一直到20世纪50年代才成为一项标准。

虽然现在看来不可思议，但是在19世纪20年代，一连串的批判性观点预测有声电影这项新“玩意儿”技术将会迅速淡出人们的视线，和第一次世界大战之前将画面与录音连接在一起的多次尝试并无二致。这些批评有一个共同的假设--早期成果的技术缺陷（同步性差、差的扩音、易损坏的录音）仍会不可避免的发生。不可否认他们对1920年代声音试验的技术缺陷的评价（与真实情况）相去不远，但是他们忽视了电影领域的新生力量，这些新力量决不接受“不”这个回答。

20世纪20年代，这些新生力量迅猛发展，出现了大量连接电话与无线技术的电子及通讯公司。在美国，还出现了像美国电话电报公司、通用电气和西屋电气这样的公司。他们对声音技术的各种形式和一切商业开发潜力非常感兴趣。这些竞争与合作开创了美国的广播产业，20世纪20年代早期开始引入商业广播节目。由于金融资产明显多于电影产业，而且他们在娱乐业与通信媒体之间的关系上前景更为广阔，因而他们使研究电影配音得到复兴。

粗略计算，1929年美国的电影产业上映的有声电影超过300部，同时还有一定数量的带有音乐伴奏的默片和两个版本都有的电影，以照顾一些未配备音响的电影院。美国于1930年最终完成生产环节上的转换。欧洲耗时更久一些，这主要因为很多小生产商无法负担的音效成本，另一部分原因是专利权和许可设备配备问题使得声音制作的转换推迟了几年（尽管很多大城市的电影院可能为了播放国外的有声电影配备了设备）。至此，有声电影取得胜利，并迅速、全面、广泛地流行起来。