Before I comment on this, I just want to point out this link below to a thread starting with post 364 where I went into the details of the differences between the More 1, 2, and 3, to be used as reference for my discussion below:
The first question I’d have is whether your audi sets the Virtual Outer Ear to Aware or Balanced. The More 2 and 3 only has 1 configuration, which is Balanced. The More 1 has 3 configurations, and if it’s set to Aware, then you’d be able to hear more sounds around you in the situations that you define as Easy Environment. I originally thought it was not much big of a deal, but @JeremyDC in a later post commented that he found Aware much better for his liking than Balanced.
The other thing is the Sound Enhancer. The More 3 has only Comfort, the More 2 has Comfort and Balanced, and the More 1 has both of those plus Detail. Again, if your audi set the Sound Enhancer on your More 1 to Detail, and the More 3 only has Comfort, then that would also help open up the sound field further for you, even with Neural Noise Suppression enabled.
The next thing that may help more is that the More 1 has 4 estimators for the Spatial Sound to help you locate the direction where the sound comes from more accurately than the 2 estimators on the More 2 and 3. This may also give you a clearer sense of sounds if you can tell where they come from better, you may notice them more.
I think those 3 things above is what makes you notice more sounds on the More 1 compared to the More 3. There is another significant difference between the More 1 and 3, the Clear Dynamics feature in the More 1 and 2 where you get 113 dB SPL wide dynamic range input that you don’t get in the More 3. But this should be more noticeable when listening to louder music which would give you better clarity, not necessarily the ability to hear more sounds clearly in more easy environments.
The last main difference is that the More 1 has 64 channel processing while the More 2 and 3 has only 48 channels. I’m not sure if the human ear has the discerning ability to notice this difference or not. But nevertheless, even if it’s not obvious, it may still lend to the overall “je ne sais quoi” quality difference that you can feel but not hear.