hearing aids exam 1

hearing aid candidacy testing

otoscopy, acoustic immittance, OAE, pure tones, speech, ABRs, CNA, hearing handicap survey

will this person benefit from amplification?

what is the key question for determining if someone needs hearing aids

can HA be soft/loud enough for HL, will patient have benefits for their HL

limits of aidable hearing questions

asymmetric losses

greater the loss of the better ear, more situations for which bilateral fitting will be BETTER than unilateral fitting for poorer ear

detection of speech/environmental sounds, monitor own voice, enhances speech reading

benefits for profound hearing loss

CI eligibility

children with bilateral severe to profound HL (2-18), children with single sided deafness (5), ≤30% multisyllabic lexical neighborhood test and NO benefit from HA

CAPD and ANSD

do NOT benefit from HA because they make all noise louder which causes more issues

cognition/dementia with HA

hearing impairment related to volume of temporal cortex, hippocampus, and parietal lobe

how do hearing aids help cognition?

moderate cognitive decline by improving social engagement and communication, decrease cognitive load and strain on auditory function

the ____ a person uses HA after onset of HL, the _____ they are to become regular HA users

sooner, more likely

locus on control

internal vs. external changes likelihood to get HAint

internal locus of control

significant influence over events and outcomes in life, more likely to get HA

external locus of control

outside forces responsible for events/outcomes, less likely to get HA

learned helplessness theory

individuals who perceive inability to control/influence events, patients give up on socializing because of HL

focusing on positive

satisfaction was shown to be higher in positive group than control, tended to use HA more and experiences less hearing difficulty

questions to patient can tell you:

level of concern, specific needs, expected benefits, influencer

difficulty with manipulation, cognitive decline, limited finances, communication difficulty

increases with age

concern for cosmetics

decreases with age

3-6% of elderly patient

percentage of patients who would be non users of HA due to lack of manipulation skills

sound quality, fit/comfort, battery life

variables related to benefit and satisfaction with HA

greater HL, more HA experience, more expensive HA

factors relating to patients claiming more benefit from HA

medical concerns to refer to physician

visible deformity of ear, drainage, sudden HL within 90 days, dizziness, unilateral HL within 90 days, ABG ≥ 15 dB at 500-2000 Hz, significant cerumen, pain/discomfort

microphone, amplifier, receiver, battery

four basic components in hearing aids

87% or 4 in 5

number of BTE devices of all HA dispensed in US

13%

amount of custom in the ear devices in US

BTE aids

RIC/RITE, RITA

RIC/RITE

most components housed behind the ear, receiver is in the earRI

RITA

all components housed behind the ear, connects to an earmold via tubing

advantages of BTE

small enough to fit behind the ear, two microphones, large enough for wireless tech, large enough for user controls, appropriate for severe losses, RITA not affected by moisture/wax

disadvantages of BTE

microphone placement, RITA less appealing, difficult to insert, RIC affected by wax/moisture

ITE

components built into hard plastic case that fits into concha/ear canal, custom construction from custom ear mold

full shell

fills the ear, extends above crus, size 13 battery

half shell

fills half shell, fully contained below crus, size 312 battery

ITC

canal aids that extend only partway along tragus wall, size 312 battery

CIC

entire aid is in EC, size 10 or 5 battery

advantages of ITE

microphone location, cosmetics, comfort, one piece easy to insert

disadvantages of ITE

fit is issue (feedback), less durable, wax/moisture in receiver, smaller batteries (less power), smaller user controls, directional mic not usually possible, occlusion effect

body hearing aid

oldest form of transistor amplification, body worn with external button receiver

eyeglass aids

components built into stems of glasses, microphone located at hinge, receiver at non hinge ear and joined to earmold via tubing

user controls

volume (gain) control, function switch/button for on/off, memory/program, volume

transducers

microphone, receiver, telecoils, direct audio input, antenna

what are transducers

takes one form of energy and makes it something else

receiver

only output transducer in hearing aid

telecoils

small coil of wire in HA that produces voltage when alternating magnetic field flows through it, picks up electro-magnetic energy and converts it into electrical voltage that is amplified

advantages of telecoils

no acoustic feedback, no ambient signals, completely contained within HA

disadvantages of telecoils

other magnetic sources can interfere, takes up room in HA, strength of telecoil varies

direct audio input

signal sent to HA amplifier via physical receiver, allows HA to interface directly with assistive listening devices

advantages of DAI

takes advantage of HA prescription, no interference

disadvantages of DAI

only available with BTEs

antenna

hearing aid users can connect directly to some devices and to other audio/video devices

bluetooth problems

takes energy and drains HA battery, creates delay between source and receiver, only 1 device can be used with same signal to both HA

creating own proprietary low energy wireless systems

how did companies fix the battery drain and speed issues of bluetooth

batteries

power supply of HA that generates electricity by putting 2 different materials in close proximity in medium that conducts electricity in form of ions

disposable batteries

zinc air activated and use zinc and oxygen as negative and positive electrons

the ____ the battery, the ____ max current, the ____ the life

bigger, bigger, longer

electrical capacity

milliamp hours provided by battery

battery life (hours)

mAh/current drain from HA

675 battery

540 mAh

13 battery

230 mAh

312 battery

120 mAh

A10 battery

65 mAh

A5 battery

35 mAh

rechargeable batteries

aids placed in device specific charging case

performance indicators of battery

energy density, charging time, charging cycles

energy density

how much power battery can hold

charging time

how long it takes to charge the battery

charging cycles

how long battery will last

lithium ion batteries

safety risk of flammable liquid, stored in room temp, poor connection with charging, future is to find solid state batteries

advantages of rechargeable HA

dexterity, charge easily, convenience

disadvantages of rechargeable HA

cost, power insecurity

how should finished earmold be?

fit ear comfortably, easy to insert/extract, have appropriate retention, provide sufficient acoustic seal, direct sound to TM without feedback, be cosmetically appealing

outer ear

almost entirely cartilaginous

ear canal

23-28 mm (adult), outer 2/3 cartilage, inner 1/3 skin covered bone

cartilaginous section

tissue lining somewhat thick (0.5-1mm), well defined subcutaneous layer

bony section

tissue lining very thin (0.1mm), no subcutaneous layer and highly vascular

good ear impression should have:

two easily recognizable bends, be smooth and somewhat porous at cartilaginous portion and smoother/less porous in bony portion

otoblock insertion

placed just past 2nd bend

otoblocks

cotton/foam, pre tied piece of thread in range of sizes

purpose of otoblocks

prevents impression material from going deeper than intended, material completely fills canal, stretches cartilaginous portion to improve acoustic seal, facilitates removal of impression

dangers of poor placement

too small/sideways, block may be pushed further down, material may go past block, material may push through eardrum

otolight

tool for inserting otoblock, illuminated plastic rod

addition cured silicone

combining 2 putties

condensation cured silicon

combining putty with catalyst

acrylic ethyl methacrylate

powder and liquid

properties of impression material

viscosity, contraction ratio, stress relaxation, shore, tensile strength, polymerization

type A low viscosity

easy to syringe, least likely to expand canal, DON’T use when tight fit needed

type C standard viscosity

putties that stretch ear tissue at least 20% more than type A

contraction ratio

shrinkage of impression, 3% or less acceptable

2-5% over 7 days

shrinkage of acrylic materials (the most)

0.1-0.7% over 7 days

shrinkage of silicone materials

stress relaxation

degree to which impression springs back to original form when manipulated, silicone BETTER than acrylic

shore

hardness of material after polymerization, higher the shore value the harder the material

tensile strength

resistance to tearing

polymerization time

5 to 10 minutes

using dental block/open jaw technique

helps to make deeper ear impression that extends 4mm past 2nd bend and expands cartilaginous portion along entire length

non custom earpieces

non occluding open domes, occluding power/tulip domes

custom occluding earmolds

regular mold, skeleton, semi skeleton, canal, canal with canal lock, full shell, half shell, hollow canal

what domes to use with Bi CROS

use non occluding domes because you don’t want to block canal with only 1 hearing ear

advantages of hard acrylic

little deterioration, comfortable, easy to modify, smooth surface, easy to clean, low change of allergic reaction, variety of colors

disadvantages of hard acrylic

doesn’t compress in narrow canal, potential for injury if ear is struck