In this audio, the main feature is the sound of a synthetic airplane. The audio begins with a low hum that gradually intensifies, mimicking the sound of an aircraft engine starting. This hum eventually transforms into a consistent, rhythmic drone that is reminiscent of a plane in flight. The sound is synthesized, giving it a distinct, slightly artificial quality compared to the natural noise of an airplane. Despite this, it effectively captures the essence of an aircraft's noise, from the initial engine roar to the steady hum while cruising in the sky. The synthetic nature of the sound adds a unique touch, creating an audio experience that simultaneously feels familiar and new.