Hearing Aids Final

what are some cons for CIC?

only omni mic, no bluetooth or t-coil, lacks buttons, not suitable for low dexterity patients, no vent, more prone to feedback, frequent repairs

how much does cupping hand behind ear amplify sound?

5-8dB

how much does an ear trumpet amplify sound?

15 dB

Who patented the telephone and when?

Alexander Graham Bell in 1876

what 3 parts does a basic HA need?

input transducer, output transducer, and an amplifier/battery

what is wrong with the crystal microphone?

sensitive to heat and humidity

what is wrong with the magnetic microphone?

sacrifices low and very high frequencies

what is wrong with the ceramic microphone?

Has high impedance so the microphone’s sensitivity is low

what microphone is modernly used?

the electret microphone

when was the integrated circuit or CHIP invented?

1964

What is a transistor?

an amplifier

What is ohm’s law?

current = voltage / resistance or volume is directly related to current, so a higher voltage produces higher current and therefore greater sound pressure

How does the length and width of tubing affect output?

a longer tube will have more low Hz emphasis, short tubing will have the opposite, and the wider the tube the more high Hz emphasis

What HA components can help with BG noise?

Telecoil, bluetooth, direction microphones

what are the programmable classifications?

single channel and single memory = class 1, single channel and multi memory = class 2, multi channel and single memory = class 3, multi channel and multi memory = class 4

battery colors and sizes smallest to biggest

size 10 (yellow), size 312 (brown), size 13 (orange), size 675 (blue)

what is the maximum voltage of a battery?

1.45 volts

battery life formula

battery capacity / battery drain = battery life

battery drain formula

battery capacity / battery life = battery drain

What are ear impressions needed for?

Custom HA’s, BTE couplers, swim plugs, ear plugs for noise protection, coupling an assistive listening device-ALD, musician filter plugs

What is said when informing consent when taking ear impression?

Fully informing each step of the ear impression procedure and the outcomes, benefits and risks associated with the process.

What is said when informing about possible complications when taking ear impression?

Informing about the nature of the treatment, the expected benefits, any probable or serious risks and side effects, alternative actions, and the consequences of not having the treatment.

What are some contraindications for ear impressions?

Impacted or excessive cerumen present in the ear canal, a foreign body is present in the ear canal, fresh blood is present in the ear.

What is risk mitigation?

A management plan in place to manage any complications that may arise or, if necessary, refer the client to a physician. when serious instances arise, they may require immediate medical intervention. Registrants must counsel the client and significant others about negative consequences that might occur as a result of the ear impression process.

What factors need to be considered when doing an ear impression?

Reduce risk of harm, produce the best possible outcome for the ear impression, status of ear tissue, type of end product needed, open vs. closed-jaw impression, type of impression material to be used, comfort and fit of end product, need to minimize feedback, ability of the client to handle the earmold, retention.

What equipment is required for ear impressions?

An otoscope with speculum, placement tool, otoblock with thread, mixing bowl or wax pad, spatula, blunt-end tweezers and/or scissors, bite-blocks, syringe or impression gun, impression materials.

What is viscosity?

How easy the material flows before curing.

What is the difference between low and high viscosity?

Low viscosity will flow easier and is good for deeper impression for a CIC, high viscosity is thicker and may be used for high gain BTE HA’s.

Why is high viscosity and shore value good for high gain HA’s?

Higher pressure is used when injecting and may result in a more snug fit earmold reducing the chance of feedback.

What does shore value refer to?

The silicone after-cure hardness. The lower the value, the softer the finished impression will be.

What is a durometer?

One of several measures of the hardness of a material.

What shore values are most common for ear impressions?

25 A, 30 A, and 35 A.

How to decide what size otoblock to use?

Slightly larger than the canal diameter

What are hybrid analog digital HAs?

They keep the signal in analog form, but a digital chip is added to control filtering effects or compression characteristics.

What type of amplifier are analog HAs usually?

Linear amplifiers with a few adjustable parameters.

What is linear amplification?

the input signal is amplified equally at all intensity levels.

When does linear amplification stop?

The gain will increase as the input increases until saturation or max power output (MPO) of the HA is reached.

What is saturation?

Point where input and gain exceed MPO of hearing aid.

What are the two classes of amplifiers?

Class A-Single Ended and Class B-Push Pull.

How do Class A Amplifiers work?

They use Hard Peak Clipping or Non-Symmetrical Peak Clipping to stop amplification over the wearer’s UCL, which in turn causes harmonic distortion.

What is Class B Amplification?

Output limiting is achieved with less distortion and higher gain and power due to Symmetrical Peak Clipping.

What hearing loss is good for linear amplification?

Conductive hearing loss or mild sensorineural loss.

What is analog frequency shaping?

The hearing aids can adjust the frequency response curve by employing Hi-Pass or Low-Pass filters to output desired frequencies.

how is analog frequency shaped?

Using trimpots that change the cut-off frequencies.

What is automatic gain control (AGC)?

Controls the amount of gain for a specific output

What is Non-Linear Amplification?

Amplification that is proportional depending on input level. Low inputs sounds are amplified with greater gain whereas higher input sounds are amplified with lower amounts of gain.

What is non-linear amplification known as?

Compression limiting or compression.

How is input compression different from output compression?

Input compression is done when the input exceeds the TK and is activated at the preamplifier (beginning). Changing the volume decreases the gain of the hearing aid, but does not change the TK. Output compression occurs after the volume control and acts on the output that exceeds the TK. However, volume control with increase the input TK.

How is compression limiting different than peak clipping?

It results in less distortion since the gain is reduced gradually as its rounded.

What are some advantages of compression?

Limits the output of HA without distortion, maintain listening comfort, optimize the use of the residual dynamic range, maximize speech recognition ability, prevent further damage to the auditory system.

What is digital sampling?

How often the signal is measured at discreet intervals.

What is the nyquist theorem?

The sampling rate must be twice as fast as the highest analog frequency desired to represent.

What is the nyquist frequency and issues surrounding it?

The nyquist frequency is the highest frequency desired. Aliasing can occur when there are frequencies sampled over the nyquist frequency, which causes distortion.

Quantization

how precisely the amplitude variations or incoming signal is measured.

Dynamic range

The difference between the floor of ability and the highest point of output before entering saturation.

What do PSAPs do?

amplify low frequencies giving the user a boost of bass (low Hz).

What are the most popular materials for earmolds?

Lucite, and UV Hard which is hypoallergenic.

When are harder materials for earmolds better?

Patients with soft or flaccid ears to help maintain shape and for easier insertion and removal.

When are softer materials better?

Higher degree of hearing loss to reduce the chance of feedback or for comfort.

what style can be modified?

skeleton can be grinded to a semi-skeleton or canal lock

Acoustic compliance

When air is enclosed in a space with solid walls, acoustic compliance occurs

The horn effect

Increases the volume of air in the canal by scooping or grinding out the canal portion of the earmold, using tubing that flares, which emphasizes high frequencies

Open Fit or CROS A and CROS B

Less material used for milder losses to maintain the natural resonance and reduce chance of feedback

Venting

Increases natural ear canal resonance and prevents occlusion

Small vs large pressure vents

small pressure vent will reduce fullness or occlusion slightly while large diameter vents will affect the gain and output to a higher degree

Parallel venting

parallel to sound bore or tube opening. Non-occluding, bleeds low Hz and emphasizes high Hz. Affects gain and output slightly

Diagonal venting

angled from the intertragal notch to the inside of the sound bore. Non-occluding mold, bleeds off extreme low Hz only

External or trench venting

Rare, reduces occlusion. Groove along the bottom of the canal portion from the intertragal notch to the tip of canal.

C.F.A

tube that maintains the internal diameter of the tubing between a BTE and the ear mold, providing a continuous unimpeded flow of amplified sound

What is the standard tubing?

#13

How does tubing change feedback?

Heavier tubing can reduce feedback as less energy will leak through the walls

What is dry tubing?

Tubing that can reduce the chance of moisture in the tubing that block sound output. Dry is for soft materials only.

How does distance change frequency response of damper?

The closer the damper is to the earmold, the more the low and mid frequencies response is lowered

What is Venting associated with?

Body, which is occlusion and increasing background sounds

What is damping associated with?

Presence, which is the feeling of distance, since too little mids can make a sound seem farther away

What is horn associated with?

Brilliance, helping make soft high frequency speech sounds audible and increasing speech perception

You are unsure of what style of earmold to order for a client. They have sensitive ears and you may need a larger or smaller earmold depending their comments and comfort. The best choice of earmold because it is easiest to physically adjust would be:

skeleton

Canal acoustics is an important part of understanding earmolds. What are two things that contribute to canal acoustics?

Ear canal resonance and venting

What are the three types of microphone currently used in hearing aids (for different listening situations such as background noise) and how do they differ from one another?

Omni-Directional: will pick up sound equally from all directions.

Directional: Will put more emphasis, or focus, on sound coming from in front of the user.

Adaptive Directional: Hearing Aid will adjust it's focus between surround sound hearing and varied degrees of directional hearing automatically

Mr. Viani is getting 182 hours out of each zinc air battery he uses in his hearing aids. Given that the battery has a capacity of 308 mAh, what is the battery drain?

1.69 mA

How many hours should Ms. March's hearing aid batteries last if the capacity is 236 mAh and the drain is 1.55 mA?

366 hours

Most common/popular battery size?

#312

What to consider when choosing the right earmold?

Ear texture

what is the best earmold for a client with a recurring ear infection and drainage?

non-occluding

What is an amplifiers function?

Provides gain to the electrical energy

When taking an impression for a CIC or IIC, what is the best choice of material to use when considering what you have practiced with and learned about in class?

pink cartridge

Other than Lucite and UV Hard, pick 3 other materials earmolds can be made of.

skin flex, oto seal, medi sil

The most common vent you will find on an earmold is:

parallel

What is this tool used for and what is it called?

Reamer: cleans glue, widens vent or sound bore

What are 2 ways to aid in earmold tube retention for a soft material and a hard material:

Tube lock and glue

A client presents a hearing aid to you and says it's dead. What are the first TWO things you check?

battery and wax guard

When first checking that a hearing aid is powered on, you cannot immediately tell there is any output(sound), what should you do?

cup in hand and listen for feedback

A client presents a hearing aid to you and says it's dead. You can easily hear it is working, you confirm this by using a listening tube and confirm it "sounds good". What is the next step you should take?

Check clients ear canal for wax or TM abnormalities

A client comes in with a ITC hearing aid. They state it works sometimes or seems to turn on and off. What could be the problem this intermittent hearing aid is having?

Dirty or wide battery contacts

A client comes in with a BTE hearing aid with a skeleton earmold and standard #13 tubing. They state it works sometimes or seems to turn on and off. What could be the problem this intermittent hearing aid is having?

Dirty or wide battery contacts, tubing collapsing when client moves head, or volume control wheel dirty or defective

Distortion is:

Scratchy or static sound, weak volume, or a motorboating effect

A weak battery or dirty/corroded battery terminals could be cause of distortion, what are TWO other possible causes of distortion?

Plugged microphone or canal mostly plugged

A client complains the hearing aids are squealing in their ear and the volume is way too high. What do you do?

Check VC settings, adjust and retrain client on proper use

An ITE hearing aid has feedback, the shell looks good, no cracks. No matter what you do, it still squeals, even when you cover the sound bore you can hear feedback. What could the problem be?

Sound tube came away from shell or receiver

A traditional BTE or Open Fit BTE with tubing can both have sound output blocked by wax. What is another physical blockage that can block sound output?

Water/moisture