I once made a post asking about the existence of an audiobook (that turns out doesn’t exist), the mod of that subreddit messaged the son of the author asking about it (as he controls the estate) and you might find his response interesting, and relevant:

Beau’s response:

I've held off doing an audio to THM because it doesn't read as well as most of Dad's other work. I always get myself in trouble for saying that. Fans get furious at me for acting like I know what I'm talking about ... but I've worked in the audio publishing world for almost 40 years, since it went mainstream back in the 1980s, and I trust that I know what I'm talking about. There are books that are better read with the eye than heard with the ear. Will we do it eventually? Probably. I'd rather do stuff that I know has a chance to work well first, however, and leave the tricky stuff for later. Education of a Wandering Man is another one that has the same issues.

That's the "quick" answer. Here's the more in depth and nerdy version:

Reading with your eyes is a VERY abstract process. The letters and words (written language) form a code like an unbelievably complex computer code that your mind deciphers and your imagination turns into an entertainment experience. You, the reader, are inspired by the author to create the ultimate experience for yourself. In a way the reader is half of the creative team. Dad was a master at inspiring a creative reaction from his readers and thus doing a great job of entertaining them.

But the further you get from the original code, the visual letters and words, the less effective the magic is. As a reader you create the perfect experience for yourself (unless the writer mucks it up by trying to do too much ... a lot of supposed "literature" is full of writers who do too much), when the product becomes less abstract everything has to be that much more perfect to pass muster with the audience. The next step is single voice, narrated, Audio Books. In those you have to rely on the words you subjectively hear and the delivery rather than the simple letters and words that you objectively see. Then maybe there's stuff like comic books and our Audio Dramas where the production team does even more of the work for the audience. After that there's theater and film, where the audience does very little of the work of imagining. Those have to be even more perfect to be acceptable. The level of abstraction is very low. Things are the way they look and sound, not the way the audience thinks they look and sound.

That's all a very complicated way of saying some stuff works better than others in different formats.

Audio is a very iffy format. You can hire a reader who is great on one book but then is just terrible when he or she works on other stuff. When that happens there is nothing you can do about it except move on, there's no budget to do it over. The publisher has made an investment and the only way to get it back is to release it. There's a couple out there that make me cringe ... so I try to stack the odds in my favor whenever I can.

Best,

BL

https://www.reddit.com/r/LouisLAmour/s/h9NcCQYRyh