All the simulations I have created at this web site are ailable for offline use.
The above simulation was created with EJS 4.
You can click "get files for offline use" button and get the jar file.
You will find ejs source code if you unzip the jar file with any UNZIP program.
Load the source with latest EJS 4 and you can switch to any sound file (.wav format) you have.
However, it is still different from the experience in real life.