A QR code is simply a web address (in this context). Any functionality the QR code accesses is essentially a website. You build a website that does what you want, and then link to it via QR codes. For example you could set up a blog using any number of website builders (Squarespace, Wix, WordPress). Each blog post would be a "stop" with an audio file, descriptive text, and commenting, all standard blog features. Make sure you are creating a fully mobile friendly blog. Most are. I would suggest that your audio actually be formatted as video with a still or graphic and open captions, solving your ADA problem.
Of course, there are any number of specialized providers who can do this for you. You could start with Stqry. WWW.stqry.com They have a broad suite of products they can match to your needs from do-it-yourself to full service. Contact Tom Rapp, firstname.lastname@example.org
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