An encyclopedia of recorded sound is like a really big book with lots of information about different sounds that have been recorded over time. It's kind of like a giant library of all the music, speeches, and other sounds that people have made and recorded on things like vinyl records, tapes, and digital files. The book tells you all about these recordings, like who made them, what they sound like, and when they were made. So if you ever want to learn about different kinds of music, famous speeches, or any other type of recorded sound, you can look it up in this big encyclopedia and learn all about it!