Trying to playback a newly uploaded file on your application? The issue may be that you have multiple copies of the audio files on your profile (and other files as well), and it is too much data for the system to scan on the form itself.
When you upload your files for one application, they then become usable for your other applications.
They are stored in a profile for you to use again on other forms. You don't need to upload your files again for each application. This is the same for resumes, headshots, etc.
The system pre-loads all of the files just in case you might want to choose headshot 1, 2, 3 or 10 (!), and thus if there are too many duplicate files (particularly video and audio, which are large), it runs out of data and there's nothing left to actually play a file.
If you have duplicate copies of files on your profile pages, clean out the duplicates from your profile. Instead of re-uploading your files each time, look for buttons that say "attach from profile" or check boxes to previously uploaded files and select the files that you wish to add. It will save you time and it will be easier to get your forms to work properly.