Earmolds and Earshells

Question 1

Two basic styles of earmolds

Answer 1

concha and canal

Question 2

Occupy the ear concha and canal, made in standard (entire concha), shell (bowl shelled out for cosmetic), skeleton (concha reduced to a ring or 1/2 ring), or non-occluding configurations

Answer 2

concha style

Question 3

Earmold incudle half-shell (cavum-concha), canal (canal aperture), and canal-lock (possesses small plastic tail extended to ear concha) configurations

Answer 3

canal style

Question 4

Benefits of manufacturing the earmold from an open mouth impression

Answer 4

eliminates the gap and provide a more secure fit

Question 5

3 requirements of a properly fitted earmold

Answer 5

acoustic seal, comfort, aesthetic appearance

Question 6

earmold needs to direct sound towards eardrum without acoustic feedback

Answer 6

acoustic seal

Question 7

Correct earmold impression requires

Answer 7

canal, concha, and helix adequately filled, canal block left attached

Question 8

softer materials, such as silicon and vinyl, are used for hearing losses greater than

Answer 8

75 dB HL.

Question 9

Characteristic: hard, durable, hypoallergenic. Easy to modify in clinic, more easily inserted. Recommended for mild to severe HL

Answer 9

acrylic

Question 10

Characteristics: semi-soft. Firm yet semi-flexible. design for added comfort over hard material. May expand to reduce leaks. Recommend for mild to profound HL, pediatric patients. Available in colors and glitter options

Answer 10

silicone

Question 11

Characteristic: very-soft. flexible material with superior sealing properties. Flexes to accommodate TMJ movement. Recommended for severe to profound HL. Good choice for sports and pediatric patients

Answer 11

soft silicone

Question 12

What does pre-molded fittings consist of

Answer 12

dome-shaped canal fitting + thin sound tubing

Question 13

advantages of pre-molded fittings

Answer 13

very inconspicuous, facilitate same-day fitting as no ear impression needed

Question 14

Vents are designed to provide some reduction of amplification of which freq allowing these to leak out of the ear

Answer 14

low

Question 15

Parallel vent

Answer 15

most commonly used.

Question 16

Diagonal vent

Answer 16

reduce low freq energy more. y-shaped. also decrease mid-freq (630-1600) gain up to 10dB.

Question 17

Advantages to venting an earmold

Answer 17

reduce unwant low freq gain and output, allow unamp sound to enter ear canal, reduce occlusion effect, releive pressure, reduce moisture build-up

Question 18

Disadvantage to venting an earmold

Answer 18

helmholtz resonator (echo or barrell effect when patient speaks) and feedback (bigger the vent the more acoustic leakage)

Question 19

As canal length increases (6 to 22 mm), the effect of venting is ____. Thus, low frequency gain ____are less (15 dB versus 30 dB) with long canals.

Answer 19

reduced, decreases =parallel venting

Question 20

The rule of thumb is that as the parallel vent size increases (1 to 3mm), low frequency gain _____ (up to 30dB) at 500 Hz and below.

Answer 20

decreases

Question 21

If you want to decrease the low frequencies, you should order

Answer 21

a short canal (6mm) and a large vent (3mm

Question 22

Pressure equalization vents (.06-.8mm) on the other hand, no matter what the canal length is, generally only decrease gain up to

Answer 22

6 dB below 250 Hz.

Question 23

if the hearing loss below 1000 Hz is 25 dB or less, an

Answer 23

open mold (large vent 3.0 mm) is recommended.

Question 24

If the hearing loss is 30-45 dB in the low frequencies, an

Answer 24

acoustic modifier or medium vent (2.0mm) is recommended.

Question 25

If the hearing loss is 50-60 dB in the low frequencies, a

Answer 25

small vent (1.0 mm) or pressure vent (.06-.88 mm) is recommended.

Question 26

When the loss exceeds 60 dB,

Answer 26

usually do not put in a pressure vent, unless the patient is occluded or their voice bothers them.

Question 27

tubing diameters are standardized according to the

Answer 27

internal diameter, most common tubing size is 13

Question 28

thin-tube fittings can result in inadequate

Answer 28

mid and high frequency gain.

Question 29

as sound travels through the tubing, standing-wave resonances occur. These create peaks in the freq response of the HA, resulting in acoustic feedback or poor sound quality

Answer 29

dampers

Question 30

To smooth out the response many manufacturers still rely on

Answer 30

plactic or metal dampes places in earhookd

Question 31

in many high-gain BTEs, a ______ damper is used to smooth out the frequency response of the hearing aid

Answer 31

680, 1000 or 1500 ohm

Question 32

THe what of the damper also has significant effect on the freq response

Answer 32

location

Question 33

Dampers, working in the mid-frequencies, primarily remove

Answer 33

unwanted peaks in the response curve, and take several forms.

Question 34

Changes in sound bore diameter affect the ______, yet chanig the bore diameter alone yeilds little to no affect since a horn is responsilbe for changes in this freq

Answer 34

high frequency response of the hearing aid.

Question 35

Vent type changes ______ Bore and Horns change _____

Answer 35

low freq high freq

Question 36

True or false The 3 mm or 4 mm diameter Libby horn is a proven method for obtaining more high frequency gain mechanically rather than electronically

Answer 36

true

Question 37

When using a ______, it is important not to modify the length of the tubing, as shortening the length can render the horn ineffective.

Answer 37

Libby horn tube

Question 38

The mechanical action of a horn is governed by the

Answer 38

length and taper of the horn.

Question 39

For any horn to be effective, the length of the horn must be at least ____. With the proper length maintained, up to 12 dB of gain between 2 kHz and 5 kHz can be obtained.

Answer 39

17 mm