How did early microphones restrict actors and camera movement in talking pictures?

During the early transition to sound, technical limitations imposed significant constraints on both actors and camera movement, leading to the observation that "the movies ceased to move when they began to talk."12

Early microphones were large, clumsy, and possessed a very limited range. Because they were typically concealed in a single, stationary location, actors were forced to remain practically motionless while delivering their lines to ensure they were picked up by the sound track.12

Furthermore, these microphones were omnidirectional and highly sensitive, meaning they captured unwanted background noise, particularly the loud whir of cameras. To mitigate this, cameras and their operators were enclosed in soundproof, glass-paneled booths known as "iceboxes." These booths were cramped, hot, and effectively imprisoned the camera, preventing filmmakers from tilting or dollying the equipment. Consequently, the combination of stationary actors and the inability to move the camera resulted in the static nature characteristic of many early sound films. These restrictions remained in place until the development of more mobile microphones, boom cranes, and soundproof camera housings known as "blimps" in the early 1930s.123