@Mountain-View5 Oh, please. Don't you think it's obvious that if the property is on a river, that the guests can assume they'll hear the sounds of the river?
People know what rivers sound like.
Suppose you could put that in your listing, and then a guest comes during low water when there are no sounds, or diminished sounds, and the guest complains that you promised river sounds and there are none. What then? Missing amenity?
I think you may be overthinking your marketing. I'm not going to click on a sound file in your listing.
What next, nature sounds? Traffic sounds? Shower sounds?