[...] unforgettable is the scene where Alex ironically hums Singin' in the Rain by Arthur Freed during the beating and rape scene at the writer's house. The scene is ironic because it creates a comparison with Kelly, who in the titular film (Singin' in the Rain, 1952) dances and sings joyfully in the rain, while Alex does nothing but beat the two unfortunate victims, ensuring that the rhythmic pauses of the song are punctuated (and highlighted) "in time" by the kicks and blows he delivers. Moreover, the power of music in this film is further emphasized by this very song: indeed, the writer will recognize Alex only after he starts to hum it.
(Karol Lapadula from radiocittaperta.it)
Clockwork Orange (singing in the rain scene) - Music Supervision & Sound Effects By Andrea Fröhlich