How much direct sound do open domes block?

[Bimodal_user]

Just picked up Phonak Audeo Spheric I90

Real Ear Occluded Respose/Gain (REOR/REOG) could provide the information if you had any additional slit leaks (rather unlikely). I mentioned about that, because slit leaks may be a main cause of underfitting in higher frequencies due to lower feedback threshold. REM could also provide the answer if gain from hearing aid is enough to overcome earplug effect in lower frequencies. Do you have manual Spheric Speech in Noise program?

Closed or open for my loss?

Why it is the concern? Yes. In REM, without any aid, you see the response near the eardrum in REUR (Real Ear Unaided Response). When you put the acoustic coupling, e.g. earmold/domes you will have measured REOR (Real Ear Occluded Response) i.e. earplug effect to be overcome by REAR (Real-Ear Aided Response) - the most important measurement.

This is a bit about earplug effect after domes. If this isn’t overcomed by gain from hearing aid, you could lose benefits from the REUG (effect from tour earlobe and ear canal resonances).

So, in your case, you have probably underfitted REAR (Real Ear Aided Response) which could be poorer in some frequencies than REUR (Real Ear Unaided Response).

There is some differences betweer “Gain” or “Response” e.g. REAR and REAG, which measures sound from hearing aid turned on, but with different philosophy. Or REUG vs. REUR.