How is music involved in the plot of singing in the rain?​

Another function of sound employed by Kelly and Donen in this scene is the use of sound as a bridge between shots. The directors use sound as a bridge in this scene in order to help maintain continuity between the seemingly unrelated shots of the flashback sequences.

Explanation:

Plot:

Don accidentally meets actress Kathy Selden. When doing that he goes to see his fans he then falls in love with her. Lina has a bad voice, and Cosmo and Don decide to dub her they use Kathy's voice which will save their movie.