Technology Offers

„SmartVent” rotation mechanism for earmolds: maximum sound quality by optimizing acoustic transmission at the hearing aids and earpieces


A team of researchers at Aalen University has developed an easy-to-use, effective ventilation principle for hearing aids or even in-ear headphones. The innovative ventilation principle enables the hearing aid user to optimize the acoustic properties for the respective hearing situation. In addition to the greatest possible ventilation and hearing comfort, the maximum performance of the hearing instruments is unleashed in acoustically complex situations. The user can manually adjust the ventilation continuously depending on the hearing situation.


The typical hearing aid is worn behind-the-ear (BTE) and fixed in the auricle with an earmold. The earmold is individually anatomically manufactured after silicone molding of the ear canal/auricle. In addition to the sound canal for coupling the hearing aid, an additional ventilation hole (vent) is usually made in the earmold whose diameter depends on the costumer’s hearing loss. In this way, the decision on the type of acoustic coupling is already determined during the fitting of the earmold.


The most efficient would be earmolds without such ventilation holes, where no direct sound can reach the eardrum. However, most users do not get along with such an earmold, since it occludes the ear tightly and the user is thus exposed to internal noise/body sounds. A compromise is therefore found for the user between, on the one hand, the best possible wearing comfort, i.e. a ventilation hole that is as wide open as possible, and, on the other hand, good hearing aid function, i.e. a ventilation hole that is as closed as possible with only a low amount of direct sound reaching the ear. Unfavorably, the aforementioned compromise between wearing comfort and hearing aid function must therefore be determined right from the beginning, without this being able to be corrected arbitrarily and repeatedly later.


No more compromise already determined at the beginning! The SmartVent consists of a sleeve and a rotary pin, which are both inserted into each other and pushed into a corresponding recess in the ventilation hole in the additively manufactured earmold. Sound travels through the extension channel open to the face of the sleeve, through the connecting hole provided in the outer wall of the control element, and from there into the inner cavity of the control element, which opens on the side of the earmold opposite the face of the sleeve and thus into the user's ear. The effective size of the vent or vent channel can then be continuously adjusted by the user by simply twisting it, depending on the acoustic situation. The extension channel runs only partially through the sleeve in the axial direction; unhindered flow through the sleeve is prevented.

 Earmold with SmartVent insert in side view (left imag Earmold with SmartVent insert in side view (left image section) and front view (right image section) Image : Aachen University of Applied Sciences
Earmold with SmartVent insert in side view (left image section) and front view (right image section) Image : Aachen University of Applied Sciences


Fields of application


Dr. Frank Schlotter
Ettlinger Straße 25
76137 Karlsruhe | Germany
Phone +49 721-79004-0
schlotter(at) |
Development Status
Prototyp / TRL5
Patent Situation
EP 20 197 509.1 pending
Reference ID
The Technologie-Lizenz-Büro GmbH is in charge of the exploitation of this technology and assists companies in obtaining a license.