I have 1000+ hours of e-education audio. If these are in tags on separate pages of my website, will search engines recognize the text said in the audio files, or do I have to add a transcription instead? Could this transcription be between the and tags, or does it look like I'm hiding information from the visitor for SEO purposes? What is the best way to get these e-learning classes indexed?
As no one has answered, hopefully this partial answer
I don't think it is explicitly stated by Google, but the weight of evidence from the SEO community, and from the results of Google voice recognition for subtitles in Youtube (which it owns) is that Google does recognise the text in audio files - this is relatively recent though (see https://blog.hotmart.com/en/audio-seo/). There is speculation that the word "Podcast" needs to be used if people are searching for the audio though, so it may be of limited benefit. (https://www.impactplus.com/blog/3-facts-you-need-to-know-about-google-indexing-spoken-words-within-podcasts is an interesting read)
Putting information between tags would not generally be considered hiding information from visitors for SEO purposes - and indeed there are whole Schemas advocated by Google which are not displayed to casual visitors. I'm believe Google is more worried about showing different content to "real" visitors the to their bot.