Young men and women shop through numerous record bins for record albums at a music store.

The transcript discusses the historical development of recorded sound, starting with a rhyme spoken into a small hand crank machine. This innovation led to the creation of a new industry, which has grown significantly over time, now generating an annual income of 2.5 billion dollars.

Discuss the relationship between the small hand crank machine and the recorded sound industry.

What is the significance of the figure '2 1/2 billion dollars' in the context of the text?