The Sound Manager is a part of the PowerPC system software. It is also a part of System 7.5 and beyond. If you have a PowerPC-based Mac, you have the Sound Manager. If you have a 68K-based Mac running System 7.5 or greater, you have the Sound Manager.
For 68K-based Macs running System 7.1, the Sound Manager can be downloaded from various online sites, including Apple's ftp site, ftp.info.apple.com.
If you need the Sound Manager, log on to the Internet and go to Apple's site. Look in the folder: