Before the 1930s, recording sound was difficult as everyone else had to remain quiet during filming so their voices would not be captured. Now, sound can be edited to create different effects. There are two main types of sound in films: diegetic sound that occurs in the world of the film, and non-diegetic sound that does not occur in the world of the film and cannot be heard by characters. Essential equipment for recording quality sound includes a camcorder with a separate microphone, an external microphone to get closer to sound sources, and a boom poll and dead cat to effectively record dialogue scenes.