Earmolds are custom molded to fit a patient's ear based on an ear impression in order to create a sound path from the hearing instrument to the ear canal and retain the hearing instrument. They come in occluding or non-occluding designs and use various materials, shapes, and bore sizes to optimize acoustic performance, comfort, and retention while fitting to the individual needs and preferences of the patient. Other coupling options besides custom earmolds include slim tubes with domes or receiver-in-canal hearing instruments.

1. 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.

2. Earmolds & Acoustic Couplings
 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.

3. Earmolds & Acoustic Couplings
 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.

4. Earmolds & Acoustic Couplings
 Earmold
An earmold with a vent hole is said to
be non-occluding.
An earmold with no vent hole is said
to be occluding.

5. Earmolds & Acoustic Couplings
 Earmold Occlusion Effect
Most custom earmold design is an
attempt to create balance between
the occlusion effect sensation and
reduction of electroacoustic feedback.

6. Earmolds & Acoustic Couplings
 Earmold
1.
2.
There are two basic types of
materials used in the construction of
custom earmolds. They are:
Hard materials
Soft materials

7. Earmolds & Acoustic Couplings
 Earmold
Variations in its shape are used for
four primary purposes. They are:
1.
2.
3.
4.
Physical appearance
Acoustic performance
Comfort
Security/retention to the head

8. Earmolds & Acoustic Couplings
 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.

9. Earmolds & Acoustic Couplings
 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.

10. Earmolds & Acoustic Couplings
 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.

11. Earmolds & Acoustic Couplings
 Earmold Comfort & Retention
Combinations of the hard and soft
materials are often considered to
determine the best patient/client
comfort and physical HI retention.

12. Earmolds & Acoustic Couplings
 Earmold Comfort & Retention
Various shapes are also considered
when determining best patient/client
comfort and retention.

13. Earmolds & Acoustic Couplings
 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.

14. Earmolds & Acoustic Couplings
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.