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The Libby Horn tube uses the horn effect based on Mead Killion's research on stepped bore design to increase high frequency response. |
Earmold Options
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The Libby Horn tube uses the horn effect based on Mead Killion's research on stepped bore design to increase high frequency response. |
The tube is a one-piece design, available in 3mm or 4mm sizes. While the 4mm size will allow up to 5dB more gain than the 3mm size, physical ear canal dimensions limit the use of the 4mm size.
As a standard practice, we will determine the size of Libby Horn, which is most suitable for the canal dimensions, and vent size, if one is ordered. Of course, if you specify a particular size, we will do our utmost to accommodate your instructions.
Generally, the 3mm Libby Horn will increase the high frequency response by 6-8dB in the 2000-5000 Hz range. The 4mm Libby Horn will increase the high frequency response by 10-12dB in the 2000-5000 Hz range.
Winter weather can sometimes create havoc with conventional PVC tubing and because of condensation, moisture build-up may bridge the tube wall to the extent that the sound bore may become occluded. This can cause the same effect to your patient as the instrument cutting out. This problem can be reduced or eliminated with the installation of a dry tube and if possible, a vent in the ear mold.
Bore Modifications
| Open Bore | Commonly used with gently sloping high frequency losses. The canal is cut short and hollowed as in the HFE and Acoustic Modifier styles made by Emsee. |
| Large Bore | A 3-4mm bore at the end of the canal that closely replicates the use of a horn tube with the attendant slight increase in the high frequencies. |
| Regular Bore | Standard 2.3mm bore most commonly used where there is a moderate to severe loss across the board. |
| Small Bore | Generally 1mm in diameter, a small bore is used in applications where low frequencies require enhancement. |
| Fishmouth | This is a bevelled cut at the end of the sound bore, rather shallow, which acts as a cerumen trap, rather than a true acoustic modification. |
Venting Configurations
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This is the preferred vent and is always installed when we are able, unless otherwise requested. The sound bore and vent pass through the canal portion of the earmold and do not intersect. |
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Also referred to as angle or branch vent and intersects the sound bore between the end of the tubing and the end of the earmold. This type of vent is generally not recommended unless space disallows a parallel vent. |
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Also known as a trench vent, this is a groove or channel along the bottom of the canal. It is used when drainage or discharge from the ear is a problem, or if there is no room to install an internal vent in the canal. |
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The most popular venting option, done as a parallel vent, space permitting, allows the hearing instrument specialist the most flexibility to choose the most appropriate vent size relative to the loss being corrected. It can be totally opened or closed in a matter of seconds, which allows for varying choice depending upon the gain setting of a particular hearing aid. |