Answer
**Sound Films:** The arrival of sound films presented a significant challenge to Mack Sennett's career. With his rise to prominence in the era of silent films, Sennett's slapstick comedies heavily relied on physical gags and exaggerated expressions to convey humor. The introduction of synchronized sound in the late 1920s demanded a shift in filmmaking techniques and storytelling methods, leaving Sennett's silent film expertise less relevant in the evolving industry.