Audio for testing purposes

I hope this is the right place to ask this question.

I am developing an app where there are many screens that play an audio voice-over or a video. Think a training sort of scenario. The app is almost ready to begin QA, and we have multiple teams doing the QA. One team is concerned with only the technical aspects of the app (we have a different team that is reviewing the actual content in-situ). To save time, since some of the audio/video files can be fairly long, I am making replacement audio/video to insert just for the technical QA team. The audio file will be about 20 seconds long and the video even shorter. There are hundreds of files throughout the app so varying them is not feasible - it will just be one audio file and one video file, reused over and over.

I'm wondering what type of audio would be best so as not to drive the QA testers insane by hearing it over and over again for hours.

My first thought was to find some kind of "on-hold" music since that is meant to be listened to on a loop by people for eternities. Is this the right way to go? I realize it will get tiresome anyway (and we can't actually loop it because the testers will need to verify that something plays in its entirety before the screen advances), but I'm wondering what would be the best "user experience" possible for the testers in this situation?

Thank you for your time!