WSU AUD 5420 week 3 hearing aid fittings

binaural hearing

using both ears to hear sounds

binaural fitting benefits

binaural hearing, loudness summation, binaural squelch, localization

loudness summation

an increase in loudness perception with the use of two ears even when the sound pressure level is the same in each individual ear (approx. 3dB increase over monaural hearing)

binaural squelch

central auditory structures are better at suppressing unwanted noise with binaural hearing vs monaural hearing; natural ability of the auditory system to hear better in background noise due to interaural phase & intensity cues

localization

listener’s ability to know the approximate direction and distance from which a sound originates

localization interaural phase differences

time; the difference of arrival of sound between 2 ears, low-frequency sounds

localization interaural intensity differences

the difference in intensity of a sound between 2 ears, high-frequency sounds; head-shadow effect

head-shadow effect

sound coming from one side of the head will have reduced intensity when it reaches the other ear

low frequency sound waves

able to refract around the head, often vowel sounds

high frequency sound waves

cannot refract around the head, often consonant sounds

auditory deprivation

research has shown unaided ear may lose speech processing ability if patient aided unilaterally due to lack of auditory stimuli

binaural interference

in rare cases, speech perception ability of poorer ear may disrupt ability to understand speech in better ear

how to test for binaural interference

by testing binaural word recognition

what calls for a unilateral fitting

auditory deprivation & binaural interference; cost is a big factor for some patients

acoustic era of hearing aids (1200s to 1800s)

non-electric sound funneling devices; two types, trumpet horn & speaking tube

the ear trumpet (1600s to 1900s)

funneled acoustic energy toward the ear, reduced background noise interference

the speaking tube (acoustic era)

increases sound pressure level, strengthens speech signal, improves signal-to-noise ratio by decreasing background noise interference

telephone invented

by alexander graham bell in 1876, invention helped transform hearing aids

telephone transmitter allowed for

greater control of loudness, improved frequency range, reduced distortion of sounds

first intelligible words transmitted via telephone

on march 10th, 1876, bell to his assistant watson “mr. watson, come here. I want to see you.”

carbon era (1900-1939)

carbon hearing aid consisted of 3 major components, carbon microphone, magnetic receiver, and a battery; internal noise & bulky

vacuum tube era (early 1900s)

first vacuum tube used in hearing aid in 1920; vacuum technology turned sound waves into electric signals & transmitted amplified speech; provided control of current fluctuations, greater amplification, wider response range, reduced internal noise, heavy/weighed up to 7 lbs

transistor era (1950s)

invented by Bell laboratories, lighter in weight, used less battery power, more durable

Zenith Royal T

first transistor hearing aid invented by Bell labs

digital era (1960s to present)

Bell labs manufactured hearing aids using digital computer technology in the 1960s; microprocessor was invented in 1970 (allowed for smaller size of hearing aids); tech that allowed pts to adjust transmission was invented in 1979, advances in technology to improve sound quality, comfort, speech understanding & reduce background noise are continuous

1996

when the first digital hearing aid was manufactured for public use

current bluetooth compatibility of hearing aids

digital/programmable, smaller behind the ear hearing aids, invisible hearing aids, water resistance, waterproof features on some, wireless options, bluetooth compatibility

Lyric

first invisible extended wear hearing aid; when the battery runs out or aid stops working, the patient receives a new aid; placed deep in ear canal by audiologist, non-custom but invisible, very costly, patient purchases a subscription every year

goal of audiologic management

to minimize the extent of any communication disorder that results from an individual’s hearing loss through use of hearing aids, assistive listening devices, aural rehab, & counseling

questions to consider in audiology

is there a hearing disorder?

can medically treatable conditions be ruled out?

what is the patient’s hearing sensitivity loss?

how well does the patient understand speech & process auditory info?

does the impairment cause limitations in life activities?

signs of hearing loss

misunderstanding people, turning up TV or radio, can’t hear high pitched sounds, asking people to repeat themselves, difficulties on the telephone, ringing in the ear or head, speaking loudly, problems in noisy environments

HHI

hearing handicap inventory

COSI

client oriented scale of improvement

APHAB

abbreviated profile of hearing aid benefit

effects of hearing loss

strained personal relationships, negative self-image, fatigue/strain from trying to hear

patient characteristics impacting hearing aid use

manual dexterity, ear canal characteristics, vision, motivation, cognitive ability, speech understanding ability, degree & configuration of hearing loss

factors leading to poor prognosis

patient does not perceive problem, not enough HL, too much HL, difficult HL configuration, very poor speech recognition ability, active disease in ear canal

4 main components of all hearing aids

microphone, amplifier, receiver/speaker, battery

microphone

converts acoustic energy into electrical energy

amplifier

increases intensity of signal, located inside the hearing aids

battery

provides electrical power for hearing aid

four battery sizes smallest to largest

10-yellow, 312-brown, 13-orange, 675-blue (color coded stickers, zinc air)

BTE

behind the ear hearing aid style

RITE/RIC

receiver in the ear/receiver in canal

ITE

in the ear

ITC

in the canal

CIC

completely in the canal

IIC

invisible in the canal

CROS/bi-CROS

contralateral routing of signal and bilateral routing of signal; microphone/transmitter worn on the ear with hearing loss, hearing aid is worn on the ear with normal hearing, info from poor ear sent to hearing aid worn on normal hearing ear; biCROS both are amplified

BAHA

bone anchored hearing aid

fully implantable

hearing aid style that is never removed, cochlear impants

earmolds

couple with BTE or RITE hearing aids, consider acoustic needs of patient, retention in the ear, physical limitations, cosmetic preferences

domes

tips that go over the receiver, can be closed, open, power, tulip, small medium large

components of BAHA

titanium implant, abutment, sound processor

when to use BAHA

aural atresia, stenosis of ear canal, chronic middle ear conditions/drainage, severe skin allergies, single-sided deafness

auditory recruitment

abnormal growth in loudness due to a reduced dynamic range

linear amplification

all sound is amplified equally

compression amplification

various input intensity levels are amplified differently, soft sounds amplified more than loud sounds, meant to address non-linear loudness growth (recruitment) found in SNHL

analog hearing aids

amplify all sounds at all frequencies equally, including background noise

digital hearing aids

amplify all sounds to different levels depending on frequency

peak clipping

hearing aid simply does not amplify sound above a certain level, may cause some distortions of the signal

output limiting compression

hearing aid drastically reduces the gain for loud input sounds but does not clip the peaks, results in less distortion of the signal

goals of hearing aid fitting

make speech & environmental sounds audible, optimize intelligibility & sound quality, ensure pt is appropriately fit, ensure that inputs are not uncomfortable or distorted, make sure fit is comfortable

adult hearing aid selection considerations

binaural (most ppl do this) or monaural fitting, hearing aid style, user preference, gain & frequency response, degree of HL, listening needs/tech level, directionality & noise suppression, cost, use of venting, channels, memories/programming

most durable hearing aid style

BTE, not subjected to wax/ear canal moisture

currently most used hearing aid

receiver in the ear bc it creates a more natural sound

occlusion

plugged up or boomy feeling in the ear due to custom hearing aids, ITE/ITC styles

gain

the amount of intensity of a signal that is added by the hearing aid

frequency response

gain produced by the hearing aid as a function of the frequency for a given input

frequency lowering technology

tech that lowers high-frequency sounds into the low and mid frequency where hearing is better

noise reduction

steady-state noise is different from speech, when noise source is identified, the gain is decreased in the frequency band where noise exists

omnidirectional microphone

mic picks up sound 360 degrees

directional microphone

amplifies sound from certain areas & attenuates sounds from other areas, accomplished w more than 1 mic, 2 or more mics are used to focus the direction towards the target sound, improves signal-to-noise ratio, meant to increase speech understanding in noisy environments

parallel vent

the sound bore & vent are parallel and pass thru the canal portion of the earmold side by side

diagonal vent

the vent intersects the sound bore in the earmold, not recommended unless the patient’s ear canal is not large enough to allow for a parallel vent

trench vent (external)

a groove or channel along the bottom of the earmold, used when drainage or discharge from ear is a problem, used when canal is not large enough for parallel vent

select-a-vent

usually parallel vent if space permits, comes w a set of vent inserts to allow flexibility in vent size

channels

frequency range is divided into channels/bands; number of channels represents the number of frequency bands that can be independently manipulated in the hearing aids

programs/memories

today’s hearing aids have automatic programs, not as many ppl use separate manual programs, higher the tech level, the more automatic the device, most digital hearing aids have 4 programs available (speech-in-noise, wind, echo, music, lecture, etc), may be beneficial for pts who prefer to have control over their devices, not beneficial for cognitive/dexterity impairments

telecoil

tiny coil of wire in hearing aid picks up electromagnetic energy given off by certain devices (phones), used in induction loop systems, takes up space, may not be available in smaller aids, when in this mode mic is shut off to eliminate feedback

pre-fitting

hearing aids are checked in to ensure appropriate aid has been received and that the aid is working appropriately before the pt’s delivery appt, verify model/style, serial numbers, listening check, electroacoustic analysis (test box measurements), pre-fitting programming, complete & file any necessary paperwork

electroacoustic analysis

test to determine hearing aid meets the standards defined by american national standards institute (ANSI), specifications provided by hearing aid manufacturer, performed in a test box

HIMSA

hearing instrument manufacturers’ software association; used to program hearing aids

NOAH

can also be used for patient management database, supports software from multiple manufacturers

informal verification measures

physical comfort, loudness, quality of speaker’s voice, quality of patient’s own voice, many pts will report occlusion effect

real ear verification measures

need to determine if the hearing aid is functioning the way it was intended to function in the patient’s ear, especially important for peds; measurements made of hearing aid output near the tympanic membrane

probe microphone

thin tube inserted into the ear canal with a mic on the end just outside the ear for real ear verification

speechmapping

examines real ear output of hearing aid in response to speech signal

fitting appointment

check of physical fit, programming, adjustments for pt’s comfort, on-ear verification, orientation

orientation instrument operation

patients must be shown how to identify right vs left, turn aid on/off, battery use (rechargeable vs disposable), use any controls/apps, know how & when to use program button (if any), use of any accessories, use of written materials for reference

orientation insertion & removal

may be greatest challenge faced during hearing aid fitting for some, depends on aid, ear, manual dexterity, & cognitive ability; custom aids are easier than BTE or RITE aids (one piece easier than 2 pieces), earmolds help when dexterity is a concern and pt doesn’t want custom

orientation batteries

pts must be able to insert & remove batteries on their own, need to be aware of battery life, cost of batteries, where to purchase, counsel on keeping batteries away from pets & kids

phase cancellation

feedback management method that inverts acoustic signal 180 degrees to cancel out feedback (noise cancelling headphone tech)

notch filtering

feedback management method that reduces gain of particular frequency causing feedback, reducing gain may impact audibility

orientation of expectations

consistent use! successful amplification is a process, adaptation period; own voice will sound different at first, everything will be loud at first, learning curve, battery use, feedback when anything close to microphone is expected, need to clean aid every day; counseling counseling counseling!

follow up appointments

ALWAYS perform otoscopy, validation measures, review maintenance, listening check, review hearing aid troubleshooting, updated audiogram if needed, updated earmolds, counseling, first follow up is typically 1-2 weeks after initial fitting