Unit 2 Class Notes PDF

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Summary

With Greg Newman. Unit 2 notes include: Types of Hearing Aids, Component Parts of Hearing Aids, Earmolds, Types of Hearing Aid Fittings, Electroacoustic Characteristics of Hearing Aids, Troubleshooting Hearing Aids, Checking Hearing Aids, Factors Affecting Speech Intelligibility in the Classroom, Pr...

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10/3, 10/10 TYPES OF HEARING AIDS *Putting your hand behind your ear will actually help increase sound by 250-1500 Hz *ear canal is about an inch long—cartilage/soft tissue makes up about 2/3 of ear canal; bone makes up last 1/3 *feedback—the whistle that comes from the hearing aid either not fitting right or turned up too loud (or both) 

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Hearing aids—small electronic device that is worn in or behind the ear that magnifies sound vibrations entering the ear making sounds louder and clearer for the user (almost all used today are digital—used with computer chip)—roughly 4-5million operations per second o Medicare does not cover hearing aids, but some others do  Medicade covers two for kids but one for adults o Size has no impact on cost—cost is based on its technology  Smaller the aid, smaller the impact o Does NOT fix nerve damage—it only helps those with nerve damage overcome their deficits Types o Behind-the-Ear (BTE)—most common fit; in general are more flexible  Has a hook that attaches to the Earmold  Must have something that goes into the ear canal  Advantages  Can be fit to any motivated HI person  Has a lot of flexibility with features  Greater gain & MPO than smaller hearing aids o Most overall power/benefit  Telecoil is stronger than with smaller hearing aids o Allows us to pair with FM systems  Only the earmolds need to be replaced as ears grow and change size/shape  DAI (direct audio input) is available (important for students) o Because the student is mostly hearing the teacher who is wearing a microphone, they may not hear a classmate speaking at another location in the room  Suitable for ears with medical problems  Types  Super power—used for significant HL; provides maximum amount of gain (roughly 80-82 dB)  Traditional—same look but smaller; less powerful—for mild HL

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Receiver-in-Canal (RIC)—little piece of wire going over ear into canal; most popular/flexible; speaker characteristic in ear canal rather than outside the ear; for severe-profound HL o AKA “Right Receiver in the Ear” o Most commonly utilized hearing aid o Open aid—don’t plug up ear all the way  Thin-Tube—Open aid that makes speech sound more natural; all electronics in body of aid with tube similar to RIC but open rather than a speaker; for moderate to moderately severe HL  *super power is most powerful, however RIC is most common  Possible issues/disadvantages  More conspicuous than smaller aids  May fall off during work or recreation  May seem more difficult to insert, remove, and adjust volume control than a smaller hearing aid o Custom hearing aids (half-shell) may be better for those with dexterity issues because it’s easier to maneuver o In-the-Ear (ITE)—“full shell” or “half shell”—fills up canal and most of outer ear (custom—must fabricate impression of person’s ear to make mold that fits right) —half shell fills bottom half of outer ear; helps with vision, dexterity, and cognitive issues  Advantages of ITEs over BTEs  Small, and therefore more acceptable  Better microphone placement than BTE o Debatable—ITEs cause you to lose your natural pinna effects while BTEs still allow the pinna to localize some sound  More secure fit  Easy to insert and remove, and to adjust volume  However…  ITEs are not generally a good option for children o Because their ears are still growing and you cannot replace a custom hearing aid  Refrain from ITEs until they are about 10-12 years old o In-the-Canal (ITC)  Advantages  Small, even less conspicuous and therefore more cosmetically appealing than ITE  A portion of the concha is left free, allowing for natural resonance and diffraction effects  Less difficulty with feedback when using the telephone, compared to ITEs

 Less wind noise due to more deeply seated microphone Possible issues/disadvantages  May not be enough gain and output because it is smaller  Telecoil is not available in all ITCs  Smaller battery size: difficulty for some people to manage  Volume control may be difficult: need a remote  Size & circuitry—if patient’s ear is very small, may not be enough room to place the circuitry in an ITC shell  Cost—more expensive than ITE o Completely-in-the-Canal (CIC)—cannot be seen  Advantages  Cosmetically appealing  Increased output because of deep canal placement  Occlusion effect is reduced  Easy to insert and remove  Reduction in wind noise since microphone is in ear canal  Reduced feedback  Possible issues/disadvantages  Limited circuits and adjustments available  Small battery requires good dexterity  More expensive than ITC  Telecoil may not be available o Implantable aids Hearing aid batteries (big to small) o 675—blue (more higher-power hearing aids)  Up to 3 weeks battery life  Seen much in school setting o 13—orange (most common)  Seen much in school setting  7-10 day battery life o 312—brown (most common)  5-7day battery life o 10—yellow (not in BTE hearing aids)  3-5day battery life 

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10/12 BONE CONDUCTION HEARING AID 

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BC hearing aids are useful for patients who have o Atresia o Unilateral HL  BC sound travels to opposite ear’s cochlea  End result: binaural hearing Types

o Traditional—vibrator is placed behind the ear and over the mastoid  Rarely used today o Implantable (BAHA)  Device is implanted surgically behind the ear in the mastoid  Used for conductive and mixed hearing losses with congenital atresia, or longstanding middle ear dysfunction o Cros  Puts a transmitter on non-hearing ear that transmits signal to receiver in the good ear  Rarely used o Bi-Cros  Same as Cros except the good ear has hearing loss that needs a hearing aid  Dead ear side still transmitter  Receiver side serves as both receiver and hearing aid  Rarely used 10/15 COMPONENT PARTS OF HEARING AIDS *all hearing aids used today are digital (uses computer chip to process sound) 

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Parts of hearing aids o Microphoneamplifierreceiver  Electro-magnetic  Electret  *can be up to 2 microphones in a hearing aid but no more than 2 o Battery—provides the energy to power the hearing aid  Made of Zinc air  Not activated until you peel the tab off  Wait 2 minutes after activating the battery before you put it into the hearing aid because it needs to fully charge o Air exposure causes chemical reaction that gives it power  Flat side is positive side  Should last 10-14 days  This depends on how often they are wearing the hearing aid o Processor/chip Types of distortion o Harmonic distortion—more frequency specific  500 Hz >  >500, 1000, 1500, 2000 Hz o Intermodulation distortion—multiple frequencies involved  500 & 300 Hz >  >500, 300, 200, 800, 600, 1000 Hz Controls/features on a hearing aid o Battery/battery compartment

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Mercury (not used anymore because it is dangerous and toxic) Silver oxide Zinc air Lithium (only if hearing aid is rechargeable) o Rechargeable—battery cannot be accessed or replaced

Sizes  5 different sizes (numbered)  Larger batteries in larger hearing aids, etc  Voltage  Should be at least 1.4 millivolts  Key chain battery tester  Red middle area; slide battery into hole  No light means dead battery o The light is either there or it’s not Volume control On/off switch  Microphone (M)  Off (O)  Telecoil (T)  Little button—multi-program button Telecoil  Copper coil in hearing aid  May be part of on/off switch or may be separate  Usually found in FM systems or landline/analog telephones  Not used as much today  Variability in performance  Not always available on all styles of hearing aids Directional microphone  Two microphones on hearing aid, vectored (one in forward facing plane, another microphone pointed towards back)  Back microphone is directional  The desired speech signal arrives from directly in front of the listener, while the surrounding noise signal receives less amplification  Most patients benefit from this  Improves the S/N  Helps people hear better in noise; can’t get rid of all background noise, but we’re trying to take the edge off to help benefit the person  Works best in BTE hearing aids  Signal to noise ratio: we want a positive signal is 60, noise is 50  We want 15-25 positive SNR

o Can locate where the hearing aid is o Adjust to different settings  Outdoors, restaurant, television, etc *bi-modal: hearing aid in one ear, cochlear implant in the other *hearing aids typically last about 5-7 years because the technology keeps improving *hearings aid volume should be set to half/two-thirds of the degree of loss 10/17 BTE: Earmolds 

Earmolds—hearing aid is still behind the ear, mold just keeps o Importance of fit—if mold doesn’t fit it could fall out, you could get feedback, pressure sores (abrasions to the ear) o Effect of wax—attenuates high frequencies; in ear canal, can plug up Earmold (as well as any hearing aid), negative impact on high speech sounds o Effect of kink—attenuates all frequencies; tubing gets bent on itself, more common to get a kink in thin tube hearing aid, has a negative effect on sound quality, impact on all frequencies (think of a water hose) o Made out of:  Acrylic—for older people, skin gets wrinkly when getting older so acrylic slides better, can’t move  Silicone—more flexible, not optimal for older people  Vinyl o Putting them in—DON’T use Vaseline! Mineral oil or baby oil would be best o Why use mold compared to dome?  Dome is harder to get into the ear, molds keep more sound in the ear for more significant hearing loss o Types  Regular or standard  Canal is occluded  Used usually with 60+ dB HL flat hearing loss  All frequencies get amplification  Vented  A small hole drilled into the canal portion of the Earmold o The vent is usually parallel to the sound bore  Used in sloping hearing losses, not greater than 60 dB  Bigger the vent, bigger chance of drowning out low frequencies  More severe the loss, greater the chance of feedback so this is not used so much with severe losses  Reasons for venting o To allow unwanted amplified low frequencies to escape from the ear canal o To release pressure to avoid a “plugged ear” sensation

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o To allow the normal input of unamplified sound Skeleton mold: there’s a piece cut out of the back; don’t need to acclusion the ear as much (takes bulk out of ear)  Used with dexterity issues, any degree of loss up to severeprofound o “half-shell” ITE Open (nonoccluding)  2.5-3.0mm of venting is considered open  Ear is unoccluded  Very little bulk  Patients love this! Has increased number of those getting treated for hearing loss by about 5%  Does NOT need to be BTE o Open means the amount of venting you can put in the hearing  Used with normal hearing ear (APD) or high frequency hearing loss not exceeding 60 dB o Used when hearing is normal in low and mid frequencies & precipitous high frequency loss (up to but not exceeding 60 dB)

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*most insurance companies do not cover hearing aids (i.e. medicade) while some insurance companies only cover one (takes 3-6months to get it approved with them) Types of hearing aid fittings o Monaural—1 ear only is fitted  1 microphone, 1 amplifier, 1 receiver  Can’t hear in noise and have no idea where sound is coming from  some people with bilateral hearing loss will still choose to get only one ear fitted with an aid because of money issues o Binaural—both ears are fitted  2 microphones, 2 amplifiers, 2 receivers  Directionality issues—2 microphones  Good ear is combo of hearing aid and receiver  Most common  Advantages  Better sound localization because of time of arrival differences, intensity differences, and phase differences  Better speech discrimination in quiet & noise  Sound quality is better  Better sensitivity to sound o CROS—1 normal ear, 1 unaidable ear  Unaidable—will not be helped by hearing aids because it is a “dead” ear

 In this case, BAHA could also be used What is unaidable?  Profound loss or no hearing  Terrible speech discrimination  Normal hearing in low & mid frequencies  Precipitous high frequency loss (>60 dB) o BICROS—1 aidable ear, 1 unaidable ear (bilateral hearing loss)  Aidable ear set-up  Microphone  Amplifier  Receiver  Unaidable eat set-up  Microphone 

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Electroacoustic characteristics of hearing aids o Input—the signal going into the hearing aid via microphone o Output—the signal coming out of the hearing aid via receiver o Gain—the amount of power provided by the hearing aid  Gain = output – input  60 dB input > > 100 dB output  Gain = 100 – 60  40 dB  Unaided vs aided thresholds on audiogram  Know how to interpret! o Saturation Sound Pressure Level: (MPO)—the greatest amount of power provided by the hearing aid  Determined by turning volume fully on, input of 90 dB SPL (this drives the hearing aid to its maximum)  SPL—actual sound pressure level  HL—what is tested in the booth o Frequency response—the frequencies to which the hearing aid (microphone) is most sensitive to picking up and amplifying  If a person has a flat audiogram, that person requires a flat/broad frequency response  If a person has a hearing loss in the high frequencies only, that person requires a high frequency response  If a person has a hearing loss in the mid frequencies only, then that person requires a mid-frequency response, etc Troubleshooting hearing aids o Problems  Hearing aid has no sound/is dead  Possible causes

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Dead battery No battery Battery not in compartment correctly Aid not turned on Perhaps build-up of cerumen in sound bore of Earmold

Feedback  Possible causes o Earmold does not fit well o Earmold not positioned correctly o Cerumen build up in sound bore of Earmold/hearing aid o Hat, scarf, or hand near microphone of hearing aid  Sound is distorted  Possible causes o Hearing aid may be on telephone mode o Computers, car engines, lighting can cause buzzing  Other electronics such as security systems or anything that sends an electromagnetic signal  Buzzing sound  Possible causes o Hearing aid may be on telephone mode o Computers, car engines, lighting can cause buzzing  Other electronics such as security systems or anything that sends an electromagnetic signal  Hearing aid works intermittently  Most often a battery problem (battery is corroded, gives no electrical current)  Possible causes o Battery is going dead/wiring is messed up o Moisture exposure o Something serious is wrong with functionality  Hearing aid sounds noisy, raspy, clicks  Possible causes o Battery is going dead/wiring is messed up o Moisture exposure o Something serious is wrong with functionality Checking hearing aids o Need:  Listening stethoscope (about $15)  Battery checker (about $3)  Live batteries & Extra batteries (labeled) (675, 13, 312—mostly likely will not need 10)  Earmold cleaner

 Wet wipes/audio-wipes  Wax Picks  Air pump  Tissues  Your own Earmold o Check:  Seating of BTE or hearing aid in ear—is it placed properly?  Red—right  Blue—left  Battery  Is it present?  Is it the correct size battery? o 312 & 13 are the same circumference o 312 is half as thick  Extra batteries (labeled)  Earmold cleaner  Wet wipes  Your own Earmold o Visual check  Earmold:  Check sound bore for cerumen—clean if present  Check for cracks  Check tubing—hard or yellowed: needs to be replaced  Make sure it is seated correctly  Hearing aid:  Check for cerumen—clean is possible  Check case of aids for dents or cracks  Check microphone for debris  Check manual switches  Check the battery compartment o Make sure it is closed o Make sure there is a cover present o Listening check:  Connect the HA to the stethoscope and speak into the aid  Present low, mid, and high frequency sounds  Check the volume control of the HA  It should turn up as volume is increased gradually  Check the sound quality  Should be good—not “tinny”, “resonating”, or “hollow”  Check to make sure the aid isn’t intermittent when it is moved, or when light pressure is applied to various areas of the case  The HA should not be producing feedback if your finger is over the sound bore

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Factors affecting speech intelligibility in the classroom o Classroom ambient noise  Noise levels  Signal to noise ratio (S/N)  Ideal S/N: normal is +15dB; hearing impaired is +25dB  Reverberation  Floor/wall/ceiling finishes o Distance from speaker  Interaction of distance & S/N & reverberation o Recommendations  If someone is hearing impaired, sit them closer to the front!

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Problems with hearing aids o No sound or intermittent sound o Sound is too soft or noisy  SLPs need to know how to fix problems during therapy! Hearing aids: dead, too soft, or too noisy: troubleshooting o Causes include  Turned off (or not turned on)  Dead battery  Battery is inserted incorrectly  Poor battery contact (crudded up)  Moisture in the microphone or hearing aid  Clogged tubing (in BTE)  Clogged tone hook (in BTE)  Change (drop) in hearing  Someone else’s (in family?) hearing aid o Actions (what to do)  Be sure the aid is turned on  Be sure the battery door is shut all the way  Replace battery (if needed)  Re-insert the battery with correct alignment  Clean the battery contacts with pencil eraser  Store in Dry Aid or Quick Dry Kit  Use a wax pick to clean Earmold or bore of HA  Take the hook off the aid (BTE) and listen to see if the aid is whistling  If none of the above solves the problem, see your audiologist! Feedback/whistling o Causes:  Hats, scarves, or hands around the microphone  Be sure nothing is blocking the microphone

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Earmold does not fit well (BTE) or HA no longer fits patient’s ear (ITE, ITC, CIC)  Possibly a new Earmold (or re-casing of ITE, ITC, CIC) may be needed Intermittent buzzing o Causes  Hearing aid may be on telephone mode  Make sure the hearing aid is not on telephone mode  Computers and car engines can cause buzzing Reminders o Always keep batteries (new&used) away from children and adults who may be tempted to swallow them  If swallowed, need to get medical attention immediately  Do NOT put batteries into a coin purse o When working with individuals with HA, have spare batteries on hand  Batteries can die with little or no warning, so have spares  This will ensure good hearing during therapy sessions o Be familiar with the parts of the hearing aid and their function so that you are comfortable with:  Checking the function of hearing aids  Reviewing and explaining the care and use of hearing aids for patients who need it o More than 50% of nursing home residents’ HAs are not functioning correctly o HAs of school children may not be functioning appropriately  Even when a monitoring program is supposedly in place o Daily checks of HAs are crucial! Professional’s role o Be an enabler o Focus on the whole child, not just the HI child o Help parents focus on the whole child o Be able to give good information o Understand the parents’ expectations for their child(ren) o Enforce realistic expectations o All parents are different  Acceptance and adjustment varies

10/26 COCHLEAR IMPLANTS *cochlea is only 28-34mm (3cm) long *Ground wire of cochlear implant makes sure they don’t have facial nerve stimulation

*cochlear implants have 22-24 electrodes *cochlear implant (wire) itself cannot be taken out/replaced but the processor can be 

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Cochlear implant—electronic device that can restore functional hearing o Cochlear implants stimulate the damaged inner ear o Brainstem implants electrically stimulate the auditory nerve directly Rationale o Benefit from hearing aids—while most hearing impaired adults and children benefit from amplification, some clearl...