where as audio setup for most people tends to suck - $10 speakers attached to an onboard sound system with the same fidelity as an ant blowing into a trumpet.

That's me using prehistoric Creative speakers next to Xeon desktop :)

And for environment, I think keyword is consistency. Unless you use really shabby assets, an unique sense creates an environment. For example Don't Starve has not the high end GFX or SFX but environment is complete in sense of creating own world imo.

I think consistency is more important than utilizing all the senses to the maximum extent possible.

In my experience, playing something like dwarf fortress is more immersive than a visually stunning game.

Like a book, the more your brain has to work to imagine the world, the less surprises there will be and thus less potential immersion breakers. Plus when you have to imagine much of the world/atmosphere yourself, you will be more focused to the content and this also increases immersion (and youll actually remember the general atmosphere/immersiveness better than if it was just a result of external input)

If you want the game world to be perfect, let the player imagine it, the mind will simply assert its perfectness with no basis at all.

As others have said, the audio design in many games is good, you just don't get it thrown in your face because it tends to be more subtle.

This is what sparks my inquiry. Sound is more of a subtle thing, but honestly I just think we don't pay enough attention to the things we hear.

There are people who are better at that, and who pay attention to it.

There are flaws in sound and in visuals due to the doppler effect and the mirage effect. And there are illusions to be found in each.

I was playing with an app on IOS called "Sound Uncovered", by Exploratorium. It explores the nuances of sound in an interactive way.

I am just realizing that I have to do sound, and that it actually is important in the type of game I am making (Not so important in Hack Run).

Currently, I am using a similish style dialog with subtitles for my voice overs, a synth app on the iPad for sound effects, and Garageband for Mac for voice recoding. Indie all the way!