Thanks for your comments, Um_bongo. I’m not sure whether your reply directly answers my question whether M&RIE can be turned off, if desired, on a ReSound MM receiver and the receiver then function in all ways like a standard ReSound receiver. I would think that should be so as even in a fully functional M&RIE receiver, at least for the One, ReSound has stated that as the noise level in an environment increases, the HA response phases out the M&RIE mics and switches to the entirely behind-the-ear mics on the body. So it seems like the One at least can function without the M&RIE receiver working.
On occlusion, there seems to be different lines of thought amongst audiologists. I started out wearing an open fit and as soon as I had my first meal or two in a very noisy restaurant, I came to the conclusion that a very open fit with open domes is worthless in dealing with noise. A lot of noise is low-frequency spectrum and the noise just leaked into my open hear canals straight to my good low-frequency hearing and made understanding conversations very difficult. I also thought with an open fit my speech recognition wasn’t as good as it might be. Putting my fingers in my ear canals seemed to help me better understand my wife’s voice.
A while back MDB posted a 2016 review article on open vs. closed fits: Article on open fit vs closed fit
from that article, I found a 2006 Widex paper on the advantages of going with a more closed fit: Article on open fit vs closed fit - #11 by jim_lewis
So after the first few months of “enjoying” an open fit, I decided to follow Don’s route and I got molds with Select-A-Vent. For the first year or two, I quite happily wore the molds with no vent. After a while, I don’t know if it was from flying in airplanes or what, I decided I’d rather go with a 1 mm vent in each mold.
I’m presuming that the options in Smart Fit to specify the type of dome or mold and the size of any vent opening in a mold actually mean something relative to the gain applied via the HA’s to low-frequency sounds and if one has little or no venting, the HA’s just transmit low-frequency sound to the eardrum at the level it was heard, as for good low-frequency hearing little or no amplification should be required but the sound needs to be reproduced by the HA’s if the vent is non-existent or very small.
The bottom line is that with a very occlusive fit, the world sounds no different to me with and without my hearing aids except for two obvious things. I don’t hear high-frequency sounds well without my HA’s and the sound of my own voice sounds different and deeper wearing my HA’s, which doesn’t bother me at all.
My molds were very well-made by ReSound. Normally, I can cup a hand over either ear and get no feedback. The DFS Ultra III feedback test (or whatever it’s called in Smart Fit) shows little or no gain control is needed in either ear.
So, based on my own experience of using a very closed fit for years, if I had molds as good as I have now, I might experience little feedback problems with M&RIE receivers. I’m well enough off that I could afford to blow a couple hundred dollars on the receivers and molds to fit the M&RIE receivers. That’s peanuts to blowing thousands of dollars on one premium high-end hearing aid only to find out that another brand or model might have been better, etc.
The view of audiology espoused in the 2006 Widex paper is that a lot of audiology is marketing a sound experience to users that doesn’t cause them to reject hearing aids, both for the patient’s long-term benefit and the financial bottom line of HA OEMs. There is the ease of using the hearing aids with cheap easily replaceable open domes, the natural sound of one’s own voice with an open fit, and so on. But I’ve tried that and I much prefer a very closed fit, especially for the opportunity it presents me to deal with noise and directionality more effectively and to control the frequency spectrum I hear more effectively with the ReSound Smart 3D app Sound Enhancer functionality.