Lecture 5 Technology Goal: To provide with auditory system with the most consistent, clear and natural hearing possible to access, develop and organize

Lecture 5

Technology

Goal: To provide with auditory system with the most consistent, clear andnatural hearing possible to access, develop and organize the auditory centersof the brain.

Source: based on Children with Hearing loss, Cole and Flexer, pg. 117.

Introduction

• The hearing aid is the most important tool in aural (re)habilitation

Introduction

• The hearing aid is the most important tool in aural (re)habilitation

• Children must use their hearing aid(s) on full-time basis in order to obtain the desired outcomes.

Introduction

• How are children different from adults when it comes to using hearing technology?

Medical Considerations

• Every child fitted with hearing aids should be referred for a medical evaluation, preferably with an otologist.

• This process should not delay the hearing aid fitting process however.

Technology

• Hearing aids (BTE, RITE, ITE/CIC/nano)• The Earmold• Cochlear Implants• Combined Electrical Auditory Stimulation (EAS)• Bone Conduction Devices• Middle ear implants• Brainstem Implants• FM systems

– Personal FM– Soundfield FM

• Bluetooth accessories

Choosing the Best Device

• Behind the Ear (BTE) device



– More durable (less cerumen, moisture issues)



– More durable (less cerumen, moisture issues)– Hearing aid does not have to be sent away

when the child’s ear grows.




when the child’s ear grows.– Custom hearing aids may not fit in small ears




when the child’s ear grows.– Custom hearing aids may not fit in small ears– Less feedback




when the child’s ear grows.– Custom hearing aids may not fit in small ears– Less feedback– Compatible with FM systems and accessories




when the child’s ear grows.– Custom hearing aids may not fit in small ears– Less feedback– Compatible with FM systems and accessories– Can be adjusted to fit almost any degree of

hearing loss, which is important if child’s hearing changes.

Behind The Ear (BTE)

• Candidacy for conventional (BTE) device:

– Child must have an ear canal and, preferably, a pinna.




– Mild to moderately severe unilateral hearing loss.





– Mild to severe bilateral hearing loss.





– Mild to severe bilateral hearing loss.– Pre-cochlear trial period for profound bilateral

hearing loss.


• Why binaural?

– To prevent auditory deprivation– To promote normal development of the central

auditory nervous system– For localization– For hearing in noise


• Important features for children:

– FM compatibility



– FM compatibility– Telecoil



– FM compatibility– Telecoil– Ability to activate or disable volume/program

buttons




buttons– Tamper-resistant battery doors




buttons– Tamper-resistant battery doors– Children’s earhooks (kiddie hooks)




buttons– Tamper-resistant battery doors– Children’s earhooks (kiddie hooks)– Extended high frequency response or

frequency compression




buttons– Tamper-resistant battery doors– Children’s earhooks (kiddie hooks)– Extended high frequency response or

frequency compression– Moisture resistant

Hearing Aid Features

• Features that are more for adults or older children than infants:

– Directional microphones (especially if there is a tight beam)




– Expansion

Expansion

• Is the opposite of compression

Linear amplification

Compression

Expansion

Input

Out

put




– Expansion– Multiple programs




– Expansion– Multiple programs– Acclimatization settings


• Receiver in the Ear (RITE):

– Is a kind of BTE hearing aid– Some advantages to having the speaker in the ear

canal– No inherent reason why these aren’t very good for

children– May be more vulnerable to moisture issues, which will

cause intermittent malfunction.– Use caution if you decide to use “open fit”

configuration! (to fit a mild hearing loss for example)

The Earmold

Choices are:

• Material• Style• Venting• Tubing• Color

The Earmold: Material

• Hard (lucite) material is most often used with adults

• For children, we use almost exclusively a soft material.– Comfort– Better seal / less feedback / less “echoing”– Durability not as much a concern because it will have

to be replaced as ear grows in any case– Safety (hard material may cause injury if child falls)

• Disadvantage of soft clear material is that the canal portion turns brown with time

The Earmold: Style

• Do not order “standard” (for old body aids)

• The main styles are:– Full shell / shell– Skeleton– Canal mold– Open (IROS) mold

• With or without full helix / extended helix

The Earmold: Venting

• Advantages:– Decreases the occlusion effect– Decreased internal noise for this with normal

low frequency residual hearing– Allows ear canal to breathe.

• Disadvantages:– More feedback / sub-oscillatory feedback– More echoes– For open fittings sound waves can cancel

each other out or be additive

The Earmold: Color

• Almost any color is available at no extra charge, including swirls

• Increases compliance for hearing aid use in preschool and elementary school age children

Cochlear Implants• Candidacy for cochlear implant:

– For babies, candidacy is based on profound bilateral sensorineural hearing loss and no measurable benefit from amplification after a 3-6 month trial period.

– Child must be 12 months of age or older to be implanted.

– No anatomical contraindications– Parents must have realistic expectations and

be committed to do all the follow-up.

Cochlear Implants• Candidacy for older children:

– A least a severe bilateral sensorineural hearing loss AND

– Poor performance on measures of speech perception in best aided condition with conventional hearing aids.

– Speech/language development has stalled or “plateaued”.

– Has shown compliance for use of conventional hearing aids in past.

Cochlear Implants• CI’s do not restore normal hearing, but they are

very good at restoring functional hearing.

• Better at providing high frequency hearing in many individuals

• Some individuals do better than others.

• Post-lingual deafness is an important predictor.

• Critical periods in development of the auditory system are very important.

Cochlear Implants

• Funding varies from province to province.

• Initial device may be covered but parents might have to pay for upgrades/insurance later.

• Child may lose all of his/her residual hearing after the cochlear implant surgery.

Bimodal Hearing

• Refers to electrical and acoustic hearing together.

• 2 applications:

1. Cochlear implant in one ear and conventional hearing aid in the other.

2. Combined EAS

Combined EAS

• The electrode is inserted differently. The surgeon attempts to preserve the low frequency hearing.

• The device is both a cochlear implant processor and a hearing aid.

• For clients with steeply sloping hearing losses (Hannah C.).

Bimodal Hearing

There is some evidence that bimodal hearing is associated with better music appreciation and, in some cases, better localization.

Bone Conduction DevicesIdeal Candidates:• Not able to use conventional hearing aid

because:1. Bilateral ear canal atresia and/or stenosis2. Medical contra-indication to using a hearing aid

(e.g. draining ear, radical mastoid surgery) AND other ear is unaidable.

Possible Candidates:• 1 and 2 above applies to one ear and can use

conventional hearing aid in other ear• 1 and 2 above applies to one ear and hearing

is normal in the other ear• Single-sided deafness

Bone Conduction Devices• More research is needed to determine

the benefits of these devices for single sided deafness and for binaural vs monaural fitting.

• Not like a conventional hearing aid– Bone conducted sound goes to both

cochleas, so both are being stimulated by one device

Bone Conduction Devices

Also:• We hear our own voice via bone

conduction, so the cochlea of a child with unilateral atresia is still getting quite a bit of stimulation. We tend to see less auditory deprivation in these cases.

Bone Conduction Devices• Can be fitted on children as young as 2

months of age, but you have to use a softband.

• Binaural fitting with softband is possible but a bit complicated.

• Children are (officially) candidates for implant surgery by age 5 years.

• Sound transmission to the cochlea is more efficient with the implant that with the softband.

Middle Ear Implants• The outside assembly looks a lot like a

cochlear implant processor.• It sends a signal to a vibrating device

that is attached to one of the ossicles.• Unlike BAHA, individuals with

sensorineural hearing losses are candidates.

• One advantage is that you don’t have to use an earmold.

Middle Ear Implants

Mainly because of cost, the only clients that are currently receiving this kind of device here are those who can’t use a conventional hearing aid for one reason or other (e.g. draining ear), AND have too much sensorineural hearing loss to be a candidate for a bone conduction hearing device.

Brainstem Implants• It is like a cochlear implant, except that the

electrode are implanted into first relay station in the brainstem, the cochlear nucleus.

• Candidacy: Same audiological criteria as cochlear implant, but can’t receive a CI for some reason:

– Cochlea has ossified after meningitis– Labyrinthe aplasia (Michel deformity) or cochlear

aplasia (no cochlea)– Cochlear nerve aplasia or hypoplasia– Acoustic neuroma (NF2)– Injury to cochlea or auditory nerve (temporal bone

fracture)

Brainstem Implants

• Only about a thousand recipients in the world so far

• Not done in Nova Scotia at this time.

Brainstem Implants• What aren’t they more common?

– Invasive brain surgery– For adults, not as effective as cochlear

implants; expect only sound awareness, improved speech reading but not speech recognition using auditory abilities alone.

• However, in Europe they are been use for children with congenital ear anomalies, and some are doing as well as cochlear implant patients

Brainstem Implants• Why the discrepancy?

• The reason is unexplained at this time

• It might be that in NF2 patients the cochlear nucleus was damaged in some way by the disease or by surgery.

• Further research will help explain this discrepancy.

Personal FM system

Soundfield FM system

Bluetooth Accessories

• This is what will help get your tween/teen patients to buy in to the technology.

• Amplification becomes part of their “system” for:– Listening to music– Hands-free cell phone conversations– Gaming– Computing

Hearing Aid Evaluation

• Earmold Impression

– Children’s ears are smaller than adults’

– At birth the ear canal length is less than 14 mm– Grows rapidly during first year

– In comparison, adult ear canal length ranges from 19mm to 34 mm (average is 25 mm or 1 inch)



– Ear tubes and tympanic membrane perforations are common in children and are not contra-indications for taking ear impressions, but always use an otoblock.

– Contraindications include:• Excessive cerumen• Foreign body in ear canal• Radical mastoid surgery• External otitis media• Skin disorders• Active drainage from middle ear



– For babies, Instamold is sometimes a better solution.


• Hearing aid selection:

– Size (small ears)– Retention (domes not recommended)– Durability– Customer service– Level of technology (new: flex programs)– Accessories


• Device selection:

– Select the hearing aid that will consistently give the child access to the sounds that he or she needs to hear and the he or she:• Is willing to wear• Is able to obtain

Setting the Hearing Device

• Hearing aid: Use manufacturer software to ``first fit`` the hearing aid, third party software to verify the programming.

• Bone conduction device: Use in-situ measurements to program device.

• Cochlear Implant: Manufacturers supply software to map the device.

Hearing Aid Software

• Provides age-appropriate targets verify that hearing aid is delivering the correct gain and output at each frequency

• Important to use real-ear measurements (REM), or at least S-REM, to that child’s ear canal size is taken into account.

REM/S-REM vs. Aided Audiogram

REM/S-REM has many advantages (see next slide

• aided audiogram is in 5 dB steps, REM/S-REM have much finer detail

• Variability in audiometric thresholds is relatively high, especially in children.

• Child’s attention may not even allow you to complete an aided audiogram.

• We are more interested in how the client hears speech at conversational levels than at threshold levels.

• Hearing aids have internal (microphone) noise, which mask low-level sounds.

• The hearing aid processor may automatically reduce the gain for soft input sounds, which will affect your aided threshold. This is called expansion.

High Frequency Amplification

• When fitting a child`s hearing aid, pay particular attention to high frequency sounds (at and above 4000 Hz)



• Hearing aids have historically provided amplification that rolled off at 4000 Hz and above.



• Hearing aids have historically provided amplification that rolled off at 4000 Hz and above.

• This is still and issue today


Why is high frequency amplification important?

• For hearing fricatives (f,s,sh).• For marking the plural and possessiveness.• For hearing higher formants and harmonics.• Improves speech intelligibility under adverse

listening conditions• Children’s voices are high frequency, and

children talk to each other

High Frequency Rolloff

Why does the high frequency response roll off?

• Tubing effects• Feedback more likely with extended high

frequency hearing aid response• Signal processing limitations of digital hearing

aids (now largely solved).• Limitations of the microphone and/or receiver

How Can we Preserve High Frequencies?

• Check that the hearing aid is programmed for an extended frequency response.

• Use horn effects in earmold• Do not use a slim tube• Receiver in the canal may help• Activate the feedback manager instead of

reducing high frequency amplification (or remake the earmold)

• Frequency Lowering

Frequency Lowering

3 types:

• Frequency transposition• Frequency compression• Frequency translation (spectral envelope

warping)

Frequency Lowering

http://www.audiologyonline.com/articles/20q-ins-and-outs-frequency-11863



When Should Frequency Lowering be Used?

• Try extended high frequency response first• Verify audibility and discrimination of high

frequency sounds (you can use the tools we saw in lecture 3: Ling 6(HL) and UWO Plurals tests. Probe microphone equipment also has special settings for high frequency sounds.

• If you are still unable to provide enough high frequency amplification, then activate frequency lowering.

When Should Frequency Lowering be Used?

• It will almost always be necessary to activate frequency lowering when the audiogram shows a sloping hearing loss that is severe/profound in high frequencies.

Setting the Frequency Lowering Response

• Use the weakest frequency lowering setting that gives you audibility of 6000-9000 Hz sounds and separation of the /s/ and /sh/ responses

• If /s/ and /sh/ overlap then you have to use a weaker frequency lowering setting

Hearing Aid Fitting

• ~ 1 hr appointment

– Program the hearing aid(s) before the appointment. You will need all of this time to fit the hearing aids and show how it works

– When you are beginning, a checklist is strongly recommended.

Hearing Aid Fitting Checklist

Insertion of earmold Right vs. Left hearing aid Battery Insertion Checking batteries and battery life Battery warning Choking hazard warning Program/volume buttons on hearing aid Remote control Bluetooth accessories Acclimatization / Instructions re: frequency of use Regular care (keep hearing aid dry and earmold/tubing

free of wax/debris) Basic hearing aid troubleshooting

UWO Pedamp

• For ages birth to 6 years

• A protocol to promote consistent hearing aid fitting, verification and outcome measures in Canada

• Includes objective and subjective measures.

UWO Pedamp: Outcome Evaluation Tools

• Hearing aid fitting details


• Hearing aid fitting details• IHP Hearing Aid Benefit


• Hearing aid fitting details• IHP Hearing Aid Benefit• Little Ears Questionnaire


• Hearing aid fitting details• IHP Hearing Aid Benefit• Little Ears Questionnaire• Peach

UWO Pedamp: Hearing Aid Fitting

1. Use hearing aid fitting software (e.g. SpeechMap)– Assumes RECD is measured whenever

possible.

2. Use SII norms

Hearing Aid Fitting Criteria

1) For hearing losses up to and including 70 dB PTA:

Determine whether your patient’s hearing aid fitting is within 5 dB of the target from 250 through 2000 Hz for average and soft speech inputs and within 5 to 7 dB of the target at 4000 Hz;

2) For hearing losses in the severe to profound range: attempt to fit as closely as possible to the prescribed target, understanding the inherent limitations in this type of fitting.

Technology

• How do you fit hearing aids based on ABR results?

Technology

• What are some of the challenges for fitting amplification on very young infants?– Parents acceptance of their child’s hearing

loss.– Small ear canals are hard to fit with earmolds– Soft, pliable ears make hearing aids “flop”.– Feedback if child is lying down or holding

head next to parent’s body– Other health concerns

Source: Coping with Hearing Loss, Cole and Flexer, page 126.

Other barriers to hearing aid use

• Hearing aid not working

• External ear infection or psoriasis/eczema

• Excessive feedback


External ear infection or psoriasis/eczema

– Consult with ENT– Consult with dermatology– Consider combination 3-cream mixture if

problem not resolving– Steroid creams generally not a good long-

term solution– Spray earmold with special disinfectant before

inserting in ear to prevent re-infection


• External feedback– The cause is often excessive cerumen– Earmold fit? Order new earmold– Crack in earmold tubing– Excessive amplification, especially in high

frequencies

• Internal feedback– Crack in hearing aid– Old (damaged) hearing aid

Documents

Lecture 5 Technology Goal: To provide with auditory system with the most consistent, clear and natural hearing possible to access, develop and organize