Horning or trumpeting is a technique used to emphasize
the high frequencies in a hearing aid to create a “Horn” in
the end of the earmold. The construction consists of an increase
in the diameter of the sound channel to a size allowable within the constraints of the canal dimensions.
High frequencies can be enhanced by enlarging the bore of the sound channel. Another earmold modification technique which increases the experience of high frequencies is to shorten the canal. Therefore, if we have a shortened canal with a large bore, we have created a high frequency emphasis earmold.
The reverse is also true. The most effective way to “choke” or reduce high frequencies through earmold modification is to reduce the diameter of the bore or lengthen the canal or both.
When requesting the “Horn” option for an earmold, the diameter will conform as closely to the standards reported in the literature as possible within the limits of the size of the ear canal.
High frequencies can also be reduced by the use of diagonal or angular vents as mentioned earlier. While this type of vent may reduce the high frequency response, it is important to realize that feedback may also occur more often than with a parallel vent.