Sound Locomotive is a term used to describe a train that produces a loud chugging sound as it moves along the tracks. The term is derived from the sound of the steam engine, which was the most common type of locomotive in the 19th and early 20th centuries. The sound of the steam engine was created by the release of steam from the cylinders, which created a loud chugging noise. This sound has become synonymous with the image of a train and is often used to evoke nostalgia for the past.