HIS 140 - Earmolds and Acoustic Couplings Overview

Earmolds & Acoustic Couplings

Earmold

It is designed/molded to custom fit a

patient/client’s ear. This custom

process is a result of an accurate ear

impression.


Earmold

There are two basic purposes for the

use of custom earmolds. They are:

1. Create a sound path from the HI to

the ear canal.

2. Retain the HI to patient/client’s ear.


Earmold

There may be either one or two holes

drilled into the custom mold. One hole is

for the tube coupling of the earmold to the

HI i.e. sound path.

The other hole is designed to allow outside

air to mix with the air inside the ear canal

i.e. ventilate.


Earmold

An earmold with a vent hole is said to

be non-occluding.

An earmold with no vent hole is said

to be occluding.


Earmold Occlusion Effect

Most custom earmold design is an

attempt to create balance between

the occlusion effect sensation and

reduction of electroacoustic feedback.


Earmold

There are two basic types of

materials used in the construction of

custom earmolds. They are:

1. Hard materials

2. Soft materials


Earmold

Variations in its shape are used for

four primary purposes. They are:

1. Physical appearance

2. Acoustic performance

3. Comfort

4. Security/retention to the head


Earmold Physical Appearance

The color of material used and, of

course, the physical size, are to be

considered when selecting a custom

earmold for the patient/client i.e.

patient/client preferences.


Earmold Acoustic Performance

The shape of the sound bore effects the frequency response and output of a HI. There are two primary effects used in earmold design.

They are:

1. Bores which widen, increase high-frequencies.

2. Bore which restrict, reduce high-frequencies.


Earmold Acoustic Performance

Acoustic performance of mid-range

frequencies may be also be modified

by the use of dampers installed within

the sound bore path of the HI.


Earmold Comfort & Retention

Combinations of the hard and soft

materials are often considered to

determine the best patient/client

comfort and physical HI retention.


Earmold Comfort & Retention

Various shapes are also considered

when determining best patient/client

comfort and retention.


Other Couplings

There are also HI which do not require custom earmolds.

There are two basic HI configurations which use other couplings.

They are:

1. Slim tube coupling w/dome in ear canal.

2. Receiver-in-canal w/dome on receiver.


Earmold couplings must be

comfortable for the patient/client.

It is important to become familiar with

the “landmarks” of the pinna and ear

canal. Let’s review these “landmarks”

on page #119 of Dillon.

HIS 140 - Earmolds and Acoustic Couplings Overview

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