In the short term, the introduction of live sound recording caused major difficulties in production. Cameras were noisy, so a soundproofed cabinet was used in many of the earliest talkies to isolate the loud equipment from the actors, at the expense of a drastic reduction in the ability to move the camera. For a time, multiple-camera shooting was used to compensate for the loss of mobility and innovative studio technicians could often find ways to liberate the camera for particular shots. The necessity of staying within range of still microphones meant that actors also often had to limit their movements unnaturally. "Show Girl in Hollywood" (1930), from First National Pictures (which Warner Bros. had taken control of thanks to its profitable adventure into sound), gives a behind-the-scenes look at some of the techniques involved in shooting early talkies. Several of the fundamental problems caused by the transition to sound were soon solved with new camera casings, known as "blimps", designed to suppress noise and boom microphones that could be held just out of frame and moved with the actors. In 1931, a major improvement in playback fidelity was introduced: three-way speaker systems in which sound was separated into low, medium, and high frequencies and sent respectively to a large bass "woofer", a midrange driver, and a treble "tweeter."