I have been teaching App Inventor for several weeks with Project Lead the Way App Creators curriculum. It is frustrating that the audio on the emulator does not work, it is making it very hard for students to test their apps. Has anyone encountered and solved this problem? Does anyone know if a specific driver is needed?
Welcome Tania.
This code works using my emulator to play a sound.
The PC you use must have speakers; they must be turned on and the volume must be turned up.
A specific driver is not needed.
What code Blocks are you using? Do you provide a sound file in Media?
Which emulator?
I having same problem, My emulator is the last version at the site (march 15 2923). When I launch, appears appinventor-5554.
I'm trying specifically using Text-to-Speech with any text. Using with ai companion it works, but in emulator, only silence.
Hello Olavo
Welcome to the community!
........ you are centuries ahead of us, I would have thought the emulator would be a lot more impressive in 2923 
Joking aside, it sounds as though that is a limitation of the current Emulator. It's good that you can use the Companion as that gives a much better idea if how the App will work and you can make some changes on-the-fly.
If you really need an Emulator, try a 3rd Party Emulator such as Blue Stacks, Memu or Genymotion.
If your PC is running Linux try Androidx86 with Virtual Box: