Not only. I received a message from Phonak Audiology Assistant:
“(…) AOV is a ventilation in which the acoustic mass of the hole is calculated, therefore not only the diameter of the ventilation is taken into account, but also its length or shape (for example, it can be narrower in one part to expand in another). Thanks to the digital design of such ventilation based on the patient’s audiogram, we can create a solution that is as comfortable as possible for the user in terms of wearing (occlusion) and at the same time not at the expense of sound quality. (…)”
Additionally: