No course transcript available yet - they might spend quite a while correcting typos in the speech-to-text transcript as Zoom would routinely make “M&RIE” as “marry” in the text, etc. The handouts associated with the course (all the slides and 3 white papers on M&RIE performance relative to standard HA’s) are available to me as a participant in the Audiology Online course listing and perhaps will be to anyone auditing audiology online when the course is available as a canned, archived session.
Below are five illustrative slides from the course.
First slide explains suitable patient conditions for fitting M&RIE receivers:
Relative to hearing loss falling EITHER entirely in the light gray areas or ENTIRELY in the dark gray areas BUT NOT BOTH AT THE SAME TIME, the following examples were given:
The patient on the right above the loss falls too abruptly from minimal low frequency loss to moderately severe high frequency loss, so the patient is both in the light minimal loss area at low frequency and the more severe gray loss area at high frequency. Don’t think the speaker ever gave an exact rationale as to why not light gray loss and dark gray loss in the same patient at the same time.
The patient on the right is a better candidate because all of his/her loss is in the moderately severe dark gray regions of the fitting curve for M&RIE receivers.
Types of domes or molds appropriate for light gray or dark gray loss regions:
Illustration of how MSG (maximum stable gain) curves impinge on fitting:
The red regions of the gain curves shown for #1, #2, and #3 are either inaccessible because the gain amplitudes there exceed the MPO (maximum possible output) of the M&RIE receiver or the descending red curves in the 2K to 4K frequency and 6K and above show feedback regions that are verboten. However, up to 10 dB of overlap (amplification) into a feedback region is considered acceptable. Therefore, patients #1 and #2 are good candidates for M&RIE receivers, patient #3, where the required fitting curve amplification would go 20 to 30 dB into the feedback region, is not.
Basically, the dotted red line at the bottom of the MPO/feedback risk frequency regions is the maximum stable gain curve in the ReSound parlance.
Someone asked for #3 if one couldn’t just implement feedback control and the speaker said, yes, you could but it would reduce the allowed amplification and be seriously off the user’s prescribed fit - or something to that effect.