The machine that I use to run real-ear verification allows me to plug in a headset so that I can listen to the sound, either played by the machine or live, as it is delivered to the patient’s ear. That is, the sound is picked up by the probe microphone that has been placed next to the eardrum and fed back to the machine and through the headset to me. I can also plug in a USB and play any recorded sound they bring while we both listen to the output of the hearing aids.
A quick listen check using a stethoset is fine and you can definitely pick up on things, but it is not always sensitive enough.
But again, listening this way is useful when there is something objective present, like a quiet ticking or a distortion sound on the letter /a/. It is less useful when the hearing aid sounds fine but the interaction between the gain and that patient’s particular ear/hearing loss sounds odd to the patient.
@MKL The Aurical Freefit will be around +€5000 depending on options, as I have been quoted few months ago (Late 2022), and I think it comes with 1 year warranty, not including setup and VAT.