My layman's understanding is that compression clips the peak volumes so the overall volume can be brought up, resulting in a flatter ("compressed") sound. It's necessary for music to be heard on earbuds and in noisy environments. When I look at the way some high-quality artists have lowered their dynamic range over time, I imagine there must have been some interesting discussions between them and the mastering engineers, wherein the latter argued that if you want this to sell, you have to let it be mastered for the devices the customers increasingly use. Either that, or the artists did not understand the issue.
The recording industry has not made it easy for the customer to figure it out either. It's a lot of trouble to find out which version of a title is the best-mastered--or a lot of fun if you enjoy the chase. I overhauled my collection a couple of years ago and ended up with a much-improved group of about 800 CDs and SACDs. The loudness-wars database is just the starting point. They don't always have the data you're looking for, and dynamic range is only one consideration. A search on the Steve Hoffman Music Forums was often required, and often led to hours of reading multiple threads to try and discern some consensus. Then there's the whole business about trying to identify used CDs, down to reading the letters and numbers faintly stamped on the inner part of the disc.
The recording industry has not made it easy for the customer to figure it out either. It's a lot of trouble to find out which version of a title is the best-mastered--or a lot of fun if you enjoy the chase. I overhauled my collection a couple of years ago and ended up with a much-improved group of about 800 CDs and SACDs. The loudness-wars database is just the starting point. They don't always have the data you're looking for, and dynamic range is only one consideration. A search on the Steve Hoffman Music Forums was often required, and often led to hours of reading multiple threads to try and discern some consensus. Then there's the whole business about trying to identify used CDs, down to reading the letters and numbers faintly stamped on the inner part of the disc.