I had the exact same problem. Here's how i fixed it:
First, download and install SonicStage. This sounds simple, but it's really not. The installer needs to be connected to a server that is permanantly shut down. WHOOPS~ However, there is still hope! An offline installer exists! Bad news, though. Most of the offline installers are actually adware or phishing links. So, i'll link it directly to you.
CLICK HERE, BOZO!
Now, some antivirus software will attempt to block or restrict the installation. You need to say, in a firm voice and a bad British accent, "Don't do that." and make sure it doesn't. How you make sure it doesn't depends on your antivirus software.
Now, even if you're using a 64-bit OS, and/or have 64-bit Java installed already, you'll want the latest 32-bit version of Java. You'll also want the latest 32-bit version of PCSP. Now, click the options tab, then configuration (or press F12). Now, click on the tab labelled "Media." There should be a box labelled "Decode audio files with SonicStage." Check that. Now, run the iso, and it should work.
If this doesn't work, make sure your speakers or headphones are working, that your volume is up, and that the emulator isn't muted. I know this sounds obvious, but we all overlook the simple solutions sometimes.