^^^^^^^ THIS ^^^^^^
The audio on almost all pinball machines from any era was designed and built using what was state of the art parts at the time. This area of electronics moved very quickly and as a result audio chips and solid state audio recording and play devices changed drastically and rapidly making something that was 'state of the art' just a year ago, wildly obsolete.
These days we take MP3 and other solid state audio (and now video as well) recording as commonplace and mainstream but it certainly wasn't in the earlier days of pinball.
Recreating these audio pinball boards is practically impossible unless newer techniques are used such as MP3.