What technique is used to ensure that the lighting and sound levels transition smoothly during a performance?

The technique that ensures smooth transitions in lighting and sound levels during a performance is referred to as a fade. A fade allows for gradual changes, making it possible for lights to dim or brighten slowly, or for sound levels to increase or decrease gently. This creates a more polished and professional appearance, enhancing the audience's experience by allowing for a seamless flow between scenes or moments.

By using a fade, designers can manipulate the atmosphere and mood without abrupt changes, which could distract or jar the audience. This technique is fundamental in theatrical productions where timing and subtlety are crucial for immersion and emotion. The other methods like crossfade or cut might produce sharper transitions, which may not provide the same gradual shift needed for smooth storytelling in theatre arts.