Unit 4: Amplification Devices
4.1 Hearing aids Parts, functioning and types
4.2 Importance of binaural hearing aid amplification
4.3 Classroom amplification system and Assistive Listening Devices
4.4 Hearing aid care, maintenance and troubleshooting
4.5 Orientation to Cochlear implants
4.1 Hearing aids Parts, functioning and types
Listening devices are used for hearing impaired individuals to compensate for their hearing loss. These devices aim at making all sounds available in the environment as well as speech of others, audible and clear for hearing impaired individuals. These devices are available in a variety of types depending on style, size, capacity (power) and technology. There are many makes/brands available commercially which vary in price range again depending on the above mentioned types.
In some situations amplification device (such as hearing aids, Cochlear implants etc) is not sufficient alone. In such cases these devices are paired with Assistive Listening Devices. Assistive Listening Devices (ALD) can be worn separately or paired with the amplification device. E.g FM system, Loop induction system etc
Another very important classification is based on the place of stimulation done by the respective devices. The device can deliver amplified sounds directly to the external ear, or directly to the hearing nerve, or directly to the mastoid bone (bone behind external ear).
Listening devices again can be broadly classified as
1) Hearing Aids
2) Cochlear Implants
3) Middle Ear Implants
4) Bone Anchored Hearing Aids
5) Auditory Brainstem Implants.
INDIVIDUAL VS GROUP LISTENING DEVICE
INDIVIDUAL LISTENING DEVICE This type is useful for one individual at a time. It is a called a personalized device. The speech and other sounds are picked up by the device and delivered to the individual wearing it. The amplification device (hearing aid or cochlear implant) has a microphone on its surface to pick up sounds/speech, which is amplified inside the device and then delivered directly to the individual s hearing system. The individual can carry it with him/her. It is totally wearable and portable. Assistive listening device also can be individual in nature e.g FM system which can be paired with individual hearing aid.
GROUP LISTENING DEVICE - As the name suggests this system aims to help a group of hearing impaired individuals at the same time with a common device. This arrangement is usually used in a special classroom. The teacher has a microphone which picks up the teacher s voice, which is then amplified and sent to headphones/receivers worn by multiple students. So the teacher s voice is heard clearly by a group of students.
Assistive Listening Devices such as loop induction system can also be installed in large areas like classrooms where a loop is installed across the room. The sounds picked up by the microphone are transformed and run through the loop. The telecoil of the hearing aids worn by individuals picks up the signal and it is heard by the individual.
The terms assistive device or assistive technology can refer to any device that helps a person with hearing loss or a voice, speech, or language disorder to communicate. These terms often refer to devices that help a person to hear and understand what is being said more clearly or to express thoughts more easily. With the development of digital and wireless technologies, more and more devices are becoming available to help people with hearing, voice, speech, and language disorders communicate more meaningfully and participate more fully in their daily lives.
Health professionals use a variety of names to describe assistive devices:
Functioning of Hearing aids
Before understanding the basic working of a hearing aid, it is essential to know the parts of a hearing aid. The basic parts are as follows:
1) Microphone
2) Amplifier
3) Receiver
4) Telecoil
5) Volume Control
6) Tone Control
7) On/Off switch
The microphone picks up sounds around it and sends to the amplifier, where the sounds are amplified and filtered in many ways and then finally sent to the receiver which is worn by the hearing impaired individual in his external ear. The hearing aid is powered by a battery. The electronic components consist of transducers, capacitors, resistors, transistors, printed circuit boards are used. An electromagnetic coil system is used to make the telecoil , which helps to hear telephone conversation, speech in induction loop systems etc.
CLASSIFICATION OF HEARING AIDS
BASED ON STYLE
The earliest of amplification system were very basic, non electronic models like ear horns, trumpets etc. Research and development led to the first electric hearing aids which gradually improvised in style and size in order to satisfy the technological advancements as well as cosmetic preference of users. Hearing impaired individuals mostly wanted hidden hearing aids so the miniaturization of size was gradually developed in hearing aid industry.
1) Body level hearing aids As the name suggests the hearing aid is worn on the body of the hearing impaired person(e.g. in the pocket/blouse). The body of the hearing aid has a cord which connects to a receiver, which looks like a button and worn in the ear of the hearing impaired person.
2) Behind the ear type These hearing aids are wearable over the pinna or behind the external ear. The basic parts inside the hearing aid are similar to body level hearing aid only miniaturized in size and advanced technology. The whole hearing aid fits behind the ear, the receiver is also housed in the hearing aid case. The amplified sound reaches the ear via a ear mould or ear tip.
3) In the ear hearing aids These hearing aids are wearable inside the ear, the body of the hearing aid sits in the ear canal with its external part/faceplate sits at the start point of ear canal i.e. concha. As these hearing aids are smaller than the previous two styles, the internal parts are yet more miniaturized and placed closer to each other in the hearing aid case. As a result these hearing aids come with a lower output or capacity as compared with the previous two styles.
4) Completely in the canal hearing aid - This type is even smaller than the previous type and sits deeper inside the ear canal. It s almost invisible from outside. As it is even smaller, it has the lowest output/capacity among all styles. This type is customized and made according to the shape and size of the ear to be fitted.
5) Receiver in the canal- It looks similar to a miniaturized behind the ear hearing aid. The receiver of the hearing aid sits in the ear canal in a separate case/tip and connected via a slim tube with the rest of the hearing aid. The capacity of the receiver can be changed depending on the hearing loss of the person
6) Bone Conduction Hearing aid In some hearing impaired persons conventional hearing aids cannot be fitted. The reason can be malformation of external ear, absence of external ear or a actively discharging ear (presence of pus discharge most of the time due to some active infection in the ear). In these cases a body type hearing aid/behind the ear hearing aid is fitted with a bone conduction receiver, which resembles the one used for bone conduction testing. The bone conduction receiver is placed on the mastoid bone behind the external ear. The amplified sound is transformed into vibrational energy and then delivered to the mastoid bone.
Technology (analog, programmable, digital)
In earlier days the basic technology used in a hearing aid was quiet simple. All the signal/sound picked up by the microphone of the hearing aid was amplified by a common factor without any other alteration. The final sound delivered was just an amplified version of the input sound. However due to limitations of the components inside the hearing aid, the sound was degraded and distorted in most of the cases as it reached the user s ears. The problem increased when the loudness of the outside sound increased or when the signal was a speech in presence of a background noise. But with the advent of technology the hearing aid industry witnessed a lot of progress within a short span of time. As computer technology advanced, processing speed increased, it was possible to incorporate many features in the hearing aid with less power consumption. Also circuit size could be reduced dramatically.
The technology followed the development path:
Analog- Analog programmable- digital- digitally programmable
ANALOG HEARING AID: These hearing aids continuously make the incoming signal louder. The circuits treat all incoming signal similarly. As the incoming signal becomes louder the analog hearing aid makes it even louder. Some sort of limiting circuits are implemented in the analog circuit, where in the amplifier stops after the incoming signal crosses a particular level of loudness. It is used in body type, behind the ear and even In the ear hearing aids. This technology seems to be helpful for severe to profound losses as compared to lower degrees. Moreover this technology works best for quiet environment. In noisy situations, speech is not clear, as speech and noise are amplified in a similar fashion. This technology will also be helpful for flat hearing losses as compared to sloping hearing losses. Usually the hearing aids using this technology come with simple controls. Other than volume control, there are certain trimmer control options (H N L). Wherein depending upon the slope of hearing loss, low/high frequencies can be emphasized. For flat hearing loss, N (normal) position is the best. Moreover the maximum power output (MPO) can also be adjusted wherein the overall output from the hearing aid can be reduced/increased according to patient s need. This technology comes with fixed gain and maximum output with minimum adjustments possible
ANALOG PROGRAMMABLE: With the development in computer technology, hearing aids could be designed with a memory. The hearing aids could be programmed in different ways and the two or three programs could be stored and retrieved from memory. The programs can be two different settings in the same hearing aid. e.g one program for indoors and one for outdoors.
DIGITAL HEARING AIDS:
Even more advancements in computer technology led to the advent of digital signal processors. Digital Signal Processors were used in hearing aids. This enabled the hearing aids to convert the input signal/incoming signal, picked by the microphone into digital signals (binary digits). This resulted in faster and much better processing i.e, the output was much better in quality and a better representation of the input signal (original sound). Many studies have shown that in the same group of persons with hearing loss, performance was much better with digital hearing aids than analog hearing aids. Special mention is the performance in challenging situations like in presence of background noise, performance with digital hearing aids is way ahead of analog hearing aids. With the digital hearing aids, the amount of amplification depended on the level of input signal. So for a soft sound, more amplification was given whereas for a loud sound very little or no amplification was given.
DIGITALLY PROGRAMMABLE HEARING AIDS: This Variety of digital hearing aids could be computer programmed. The hearing aid has multiple memories, in which different programs can be stored. The user can change the programs according to specific needs, either with a tiny switch on the hearing aid or with remote control. These hearing aids can be programmed with the help of certain software, which are unique to various manufacturing houses. The hearing aid is connected to the computer via a programming interface. Special adaptors and cables are used for this purpose. Recently the whole arrangement could be made wireless, reducing the need of cables.
These hearing aids come in a variety of capacities, with minimum features to ample features including noise reduction strategy, feedback cancellation, and special treatment to sudden, loud sounds, enhancement of soft sounds, special treatment to speech sounds etc. The price range differs depending on capacity. This type of hearing aids is contemporary, with most of the hearing impaired population fitted with this type. These are also available and approved by Govt.of India, under the ADIP scheme.
4.2 Importance of binaural hearing aid amplification
If you have hearing loss in both ears, which is called binaural hearing, you will probably be a candidate for two hearing aids also referred to as binaural amplification.
While perhaps intimidating at first, hearing aids allow a hearing impaired person to experience sounds they may not have heard or heard properly for a long time such as the sounds of birds, group conversations and music. Usually during your hearing aid trial, you will first be fitted with two hearing devices so you can experience binaural amplification similar to the way you would trial a pair of glasses for a problem with your vision. Although you may later decide to purchase only one hearing aid, there are benefits to wearing two.
4.3 Classroom amplification system and Assistive Listening Devices
In classrooms, where the area is large, the hearing impaired individual may face difficulties to hear speech of teacher and peers due to distance and effect of other factors such as noise and reverberation. In such situations hearing aids alone may not be useful; some additional assistive devices may be helpful. These devices can be useful for one individual at a time or can be used in a group of individuals.
INDIVIDUAL DEVICES
Speech Trainer: This device comes with a microphone for the speaker, the amplifier and headphones to be worn by the hearing impaired individual. The use of speech trainers have reduced in recent times, though many old schools still use these systems. The speech trainer comes with certain controls, where the output of the signal can be altered. The headset also comes equipped with a microphone, so that the user can hear own voice. This is also used during speech therapy sessions. Usually it is worn separately without the hearing aids.
Advantages
The teacher /trainer s speech reaches the individual s ear easily and is less affected by the noise and reverberation in the room. As the signal is going mostly in the ear canal, hearing becomes much easier.
Usually these trainers come with high output capacity, so can be used for severe to profound hearing losses.
Limitations
Since it s a wired system, the mobility of the student and teacher is affected.
Cannot be used in groups.
Useful only for one to one teaching.
Personal neck loop system- The speech of teacher is picked up by a microphone worn by the teacher and sent to a loop worn by the student whose hearing aid is at telecoil position. The signal in the loop is picked up by the hearing aid and amplified.
FM System- These based on FM technology. These are typically used in schools. The teacher wears a microphone that is either clipped on to their collar or as a headset. This is connected to a transmitter, which sends out FM signals to the receiver unit worn by the student. It can also be carried around in the pocket everywhere. It helps reduce the background noise and improves speech clarity even at a distance. It can be used by a hearing impaired student in a normal classroom. It can be used as a individual or group device.
Personal amplified system
Personal amplifiers are useful in places in which the above systems are unavailable or when watching TV, being outdoors, or traveling in a car. About the size of a cell phone, these devices increase sound levels and reduce background noise for a listener. Some have directional microphones that can be angled toward a speaker or other source of sound. As with other ALDs, the amplified sound can be picked up by a receiver that the listener is wearing, either as a headset or as earbuds.
GROUP CLASSROOM AMPLIFICATION DEVICES
Hardwired ALDs use an actual cord or wire to transmit the sound, thereby tethering the listener to the sound source. A hardwired ALD is typically lower in cost, easy to use, and is very portable. It is excellent for situations where the listener-to-speaker distance is not too great, such as in an automobile, restaurant or for TV viewing. It is also excellent as a temporary form of amplification such as may be needed in a doctor's office, hospital or nursing home. A disadvantage of the device is restricted mobility and limited seating arrangements which are dictated by the length of the cord. This limits the usefulness of a hardwired ALD in larger communication situations such as in a classroom, meeting or tour group.
There are five general types of assistive listening devices: audio induction (also called a hearing) loop, FM system, infrared system, personal amplified system and Bluetooth systems. The right device for you can depend on your hearing loss and where you need communication access.
Advantages
Disadvantages
Audio induction or hearing loop
Hearing loop (or induction loop) systems use electromagnetic energy to transmit sound. A hearing loop system involves four parts:
Amplified sound travels through the loop and creates an electromagnetic field that is picked up directly by a hearing loop receiver or a telecoil (see sidebar), a miniature wireless receiver that is built into many hearing aids and cochlear implants. To pick up the signal, a listener must be wearing the receiver and be within or near the loop. Because the sound is picked up directly by the receiver, the sound is much clearer, without as much of the competing background noise associated with many listening environments. Some loop systems are portable, making it possible for people with hearing loss to improve their listening environments, as needed, as they proceed with their daily activities. A hearing loop can be connected to a public address system, a television, or any other audio source. For those who don t have hearing aids with embedded telecoils, portable loop receivers are also available.
Advantages
Disadvantages
FM system
FM systems use radio signals to transmit amplified sounds. They are often used in classrooms, where the instructor wears a small microphone connected to a transmitter and the student wears the receiver, which is tuned to a specific frequency, or channel. People who have a telecoil inside their hearing aid or cochlear implant may also wear a wire around the neck (called a neckloop) or behind their aid or implant (called a silhouette inductor) to convert the signal into magnetic signals that can be picked up directly by the telecoil. FM systems can transmit signals up to 300 feet and are able to be used in many public places. However, because radio signals are able to penetrate walls, listeners in one room may need to listen to a different channel than those in another room to avoid receiving mixed signals. Personal FM systems operate in the same way as larger scale systems and can be used to help people with hearing loss to follow one-on-one conversations.
Advantages
Disadvantages
Infrared system
Infrared systems use infrared light to transmit sound. A transmitter converts sound into a light signal and beams it to a receiver that is worn by a listener. The receiver decodes the infrared signal back to sound. As with FM systems, people whose hearing aids or cochlear implants have a telecoil may also wear a neckloop or silhouette inductor to convert the infrared signal into a magnetic signal, which can be picked up through their telecoil. Unlike induction loop or FM systems, the infrared signal cannot pass through walls, making it particularly useful in courtrooms, where confidential information is often discussed, and in buildings where competing signals can be a problem, such as classrooms or movie theaters. However, infrared systems cannot be used in environments with too many competing light sources, such as outdoors or in strongly lit rooms.
Advantages
Disadvantages
Bluetooth system
4.4 Hearing aid care, maintenance and troubleshooting
Hearing aid maintenance is important for well-functioning and long-lasting hearing aids. Even though hearing aids are very durable and can withstand the stresses of daily use, hearing aid maintenance is necessary to make sure you re getting the best sound quality and longevity out of your devices.
Along with specific use of the hearing care, maintenance is another area patients need to work for a successful orientation to their devices. Care includes how a patient needs to handle the devices to ensure they remain in working order. Maintenance includes activities that need to be completed on a semi-regular basis for routine upkeep. No matter the model, bundled or unbundled, that the clinic follows, audiologists want their patients to be able to manage their devices. Being a support to patients during the orientation will make them they are more independent over time.
Care and maintenance vary from daily activities to those that need to be completed on an as-needed basis. Ensuring patients are aware and capable of completing care and maintenance is critical during hearing aid orientation. As previously discussed, improper use of hearing aids can result in outcomes that are the opposite of the intention and the same can be said for care and maintenance. If a patient does not properly care for their hearing aid, it is possible that they could encounter effects that make hearing and communication more difficult. An example of this is the common result of cerumen build up in a hearing aid. If this is not properly cared for, it is possible the patient will have a more difficult time hearing with their hearing aid even if it is in properly and they are fully aware of how to use the device.
Care and maintenance
Daily
Regularly
Change the Wax Guards
Ear wax and moisture are the leading causes of hearing aid malfunction and poor performance. Wax guards prevent these from entering the sound outlet of your hearing aid and damaging the speaker. We recommend you replace your hearing aid s wax guards every 2-4 weeks depending on how dirty your wax guards become.
1. Before touching your hearing aids, wash your hands with soap and warm water.
2. Remove the ear bud or receiver earmold from your hearing aid.
3. Take out the new wax guard. Using the back side of the stick, insert the stick into the sound outlet and pull firm to remove the old wax guard.
4. Flip the stick over to insert the new wax guard.
5. Replace the ear bud or receive earmold.
6. Wash your hands thoroughly before inserting your hearing aids.
Troubleshoot at home. Many times, minor issues can cause your hearing aids to function poorly or stop working altogether. Before you visit a hearing aid specialist for repair, try removing and replacing the battery, cleaning the battery apartment, checking all programming and settings, removing and reinserting the device, and replacing tubing and wax filters.
Troubleshooting Common Problems
Occasionally your hearing aids may encounter malfunction. Fortunately, some malfunctions can be resolved at home, saving you time and money. Let s walk through some common minor malfunctions that you may experience that you can solve yourself.
My Hearing Aids Won t Turn On
First, check whether your hearing aid batteries are dead; you may need to replace them. For rechargeable models, check that your devices are charged; if the battery indicator is not illuminated, your hearing aids need charging.
Also make sure the batteries are facing the correct direction (+ with + and with -).
Second, check whether the door of your device s battery compartment is fully closed. A loose or open door will prohibit the devices from functioning.
I Can t Hear Any Sound Coming from My Devices
First, check your hearing aid s volume: is the volume turned down all the way or set to mute?
Next, check whether your hearing aid batteries are dead; you may need to replace them. For rechargeable models, check that your devices are charged; if the battery indicator is not illuminated, your hearing aids need charging.
Last, physically examine your hearing aids for any obstructions like ear wax buildup which can clog the microphone, speaker and/or receiver. If necessary, clean your hearing aids and consider replacing their wax guards.
The Sound Quality Is Muffled or Gargled
First, check whether your hearing aid batteries are dead; you may need to replace them. Dead or dying batteries will affect your device s sound quality.
Next, physically examine your hearing aids for any obstructions like ear wax buildup which can clog the microphone, speaker and/or receiver. If necessary, clean your hearing aids and consider replacing their wax guards.
The Volume Is Too Loud and/or Too Quiet
First, check your hearing aid s volume: is the volume turned down all the way or set to mute?
Next, double check whether you re using the most appropriate program for your current situation. Some programs are designed specifically for phone conversations or noisy environments and therefore may not be appropriate for everyday situations.
Utilize your audiologist. Anytime you re concerned that you are not getting the most out of your hearing aids, you should schedule an appointment with your audiologist. Today s devices are very complex and imperfect programming can have a substantial effect on how well your hearing aids are performing.
Don t forget your warranty. Hearing aids are always backed by a manufacturer s warranty; it is important to remember the terms of your warranty to ensure you get any repairs you need. If your warranty is running out soon, come see us for a warranty repair and check appointment to make sure there are no problems with your devices.
4.5 Orientation to Cochlear implants
A cochlear implant is an electronic device that improves hearing. It can be an option for people who have severe hearing loss from inner-ear damage who are not able to hear well with hearing aids.
Unlike hearing aids, which amplify sound, a cochlear implant bypasses damaged portions of the ear to deliver sound signals to the hearing (auditory) nerve.
As part of the cochlear implant process, a pre-implant evaluation is necessary to determine whether an individual is a candidate for a cochlear implant. Ideally, a cochlear implant candidate is someone who is likely to obtain more benefit from an implant than from traditional amplification (hearing aids). In addition, it is important to ensure that potential recipients and their families are well informed regarding all aspects of cochlear implantation. The evaluation process typically involves consultation with various professionals and comprehensive testing in order to fully determine the individual s level of communicative function. The following appointments may be included in this process:
Cochlear Implant Orientation
The purpose of the orientation is to provide the child and the family with information regarding the cochlear implant and the implant process. Topics discussed typically include:
How cochlear implants work
Available devices and the differences between them
Surgery and follow-up procedures
Expectations for a young child/adult who receives an implant
Need for on-going special services following implantation
Audiological Evaluation
During the audiological evaluation, an audiologist will measure the potential recipient s hearing levels with and without hearing aids. Testing can involve active participation (traditional hearing testing) and/or the use of special machines (otoacoustic emissions, tympanometry). Typically, the audiologist will also evaluate the individual s understanding of speech both with and without the use of hearing aids. In a young child, the audiologist will evaluate the child's meaningful listening skills. Based on the test results, the audiologist may recommend a trial with a different set of hearing aids (e.g., high power hearing aids or frequency compression aids).
Vestibular Evaluation
Because of the proximity of the hearing and balance (vestibular) organs within the inner ear, vestibular testing will typically be conducted to look at the health of the candidate s balance system.
Medical Evaluation
At this evaluation, the ear surgeon will discuss issues regarding the medical and surgical aspects of cochlear implantation. In addition, the physician will obtain information about the candidate's medical and hearing health history, conduct an ear examination, and review available x-rays and test results to determine whether the child can safely undergo the surgical procedure and whether there are any medical or structural problems that could prevent successful insertion or use of a cochlear implant.
CT Scan
This is a special type of x-ray that is used to provide the ear surgeon with information regarding the status of the cochlea and may indicate which ear would be better to implant. The physician is interested in whether the cochlea and auditory nerve canal have a normal shape and whether there is bony growth that can potentially compromise insertion of the cochlear implant electrode array (e.g., in cases where the child has had meningitis).
Speech/Language Evaluation (For Children)
A speech/language pathologist conducts an evaluation that looks at the child s overall communication abilities, including receptive and expressive language, functional auditory skills and speech production as well as the child s potential for growth in these areas. Parent questionnaires are usually used to gather information if the child is very young. Standardized tests administered in the child s primary mode of communication are used with older children. The results of this evaluation are used to determine the child s areas of strength, to identify ways to help the child further develop communication skills, and to serve as a baseline from which to compare subsequent performance.
Functional Communication Assessment (For Adults)
A speech/language pathologist will assess the impact of the candidate's hearing difficulties on communication and quality of life. A test is also administered to screen for any cognitive issues that could affect outcomes. A plan for listening therapy services after the cochlear implant is in place will be discussed.
Expectations Discussion
The purpose for discussing expectations is to determine if a candidate/family has a good understanding of the benefits and limitations of a cochlear implant device. The following topics may be discussed with the child and/or family:
What factors led to an interest in cochlear implants?
How have the individual and family adjusted emotionally to the hearing loss?
Are there socialization issues that are of concern?
Has the individual's hearing loss affected school or job performance?
What are the family's expectations for the individual's performance with the cochlear implant?
Are expectations realistic? Has the family talked with other implant users?
How supportive are the immediate and extended family members to the idea of an implant?
How committed will the family be to follow-up visits or therapy?
What type of educational support services are available?
What does the individual or family know about the Deaf Culture's view regarding cochlear implants?
What information is needed about assistive devices in addition to the cochlear implant?
What information is needed about support groups and individual counseling?
CANDIDACY
1. Hearing impaired individuals with severe to profound hearing loss.
2. Individuals who do not benefit from hearing aids or get limited benefits.
3. Individuals whose aided performance on speech perception tests is less than 50%.
4. No benefit from hearing aid, 3 months post fitting with hearing aids.
5. No other psychological deficits 6. No problems/disorders in higher processing centres.
7. Intact auditory nerve
These implants usually consist of 2 main components:
Currently made devices have a magnet that holds the external system in place next to the implanted internal system. The external system may be worn entirely behind the ear or its parts may be worn in a pocket, belt pouch, or harness.
Cochlear implants use a sound processor that fits behind the ear. The processor captures sound signals and sends them to a receiver implanted under the skin behind the ear. The receiver sends the signals to electrodes implanted in the snail-shaped inner ear (cochlea).
The signals stimulate the auditory nerve, which then directs the signals to the brain. The brain interprets those signals as sounds, though these sounds won't be just like natural hearing.
It takes time and training to learn to interpret the signals received from a cochlear implant. Within 3 to 6 months of use, most people with cochlear implants make considerable gains in understanding speech.
A cochlear implant uses a sound processor that's worn behind the ear. A transmitter sends sound signals to a receiver and stimulator implanted under the skin. They stimulate the auditory nerve with electrodes that have been threaded into the cochlea. Some types of cochlear implants have one outside unit that has a speech processor, microphone and transmitter combined (lower left). Others have these as separate outside parts (upper left and on right).
Middle ear implant
Middle ear implants are suitable for those with a mild-moderate mixed or conductive hearing loss or a sensorineural hearing loss.
A middle ear implant is a more recent hearing implant, offering an alternative to conventional hearing aids. It may be considered for those who suffer with earmould allergies, skin problems in their ears, outer ear infections, narrow, collapsed or closed ear canals, or malformed ears.
It can also provide (for mixed or conductive hearing
losses) an alternative to a bone anchored hearing aid for those with any
of the above ear problems who also have healing issues, dexterity problems, or
those who might find difficulty in keeping a bone anchored hearing aid clean.
Hearing aid selection procedures orientation
Conducting an orientation that is device-centered is important for all hearing aid users to ensure the patient is familiar with their instruments. For new hearing aid patients, a device-focused conversation provides them with the foundational knowledge needed to feel confident with their hearing aids.
The Basics of Hearing Aid
Selection
Hearing aid selection is a complex part of hearing rehabilitation. The
selection process follows the clinician s assessment of a patient s candidacy
for amplification, and precedes the hearing aid fitting, verification, and
validation processes.
When the decision in favor of treating the particular case in point is made, the clinician is confronted with multiple decisions to customize the client s treatment with amplification. The clinical challenge is to weigh the many factors in the selection process to achieve an optimum fitting. It is a fact that there is not just one possible hearing aid fitting per patient. Therefore, patients and clinicians usually have many choices in the selection of treatment. Essentially, the patient s goals, the clinician s assessments, and all of the potential fittings somehow must merge during the fitting process to arrive at the most successful rehabilitation outcome. It should be obvious that many experienced professionals have developed their own way for accomplishing this objective, and these methods may deviate substantially from the methods presented here.
An everyday three-part categorization may provide a practical framework for the selection process used in most practices:
1. Clinical Considerations
a. Type of hearing loss (sensorineural, conductive, or mixed);
b. Degree of hearing loss (mild, moderate, severe, or profound);
c. Sensitivity to sounds, tolerance/recruitment problems, and dynamic range;
d. Psychological attitude toward correction (eg, motivation and the primary
motivator);
e. Contraindications for correction.
2. Physical Conditions of the Patient
a. Shape and size of ears and ear canal;
b. Manual dexterity and finger sensitivity;
c. Mental acuity.
3. Patient Wishes/Preferences
a. Cosmetic;
b. Needs assessment;
c. Appropriate circuit choices (digital, programmable, etc);
d. Appropriate controls (eg, AGC, VC, remote control, directional microphones,
etc).
Selection by
Physical and Cosmetic Factors
Even before electronic devices were available, the hearing-impaired population
was very concerned about the appearance of hearing aids. The concern is based
on the perceived message that hearing aids are a visible indicator of declining
faculties. This change potentially involves the way people think about the
patient and what kind of message that patient is broadcasting to other people.
This message, in reality, relies on human interaction and involves that most
powerful commodity: self-perception or self-actualization.
Today, most patients have numerous cosmetic options from which to choose. There are a few groups of hearing losses that cannot use certain cosmetic options due to acoustic performance limitations.
The dispensing professional is confronted with a conundrum when assessing the physical/cosmetic factor. Trying to provide the cosmetic choice of the patient is important. But, should the size of the aid be the primary factor in selection of the hearing aid style? Remember, patient motivation is highly connected to the time the hearing instrument is used by the patient and effective hearing correction.
Selection by
Physiological, Anatomical, and Dexterity Factors
The anatomical parameter of the hearing aid selection process includes otoscopy
and a general examination of the ear canal and external ear. The physical
status of the entire external ear and eardrum is important in the hearing aid
selection process. It should be noted that all external ears differ as much as
fingerprints differ from person to person. The right and left ear of the same
individual can differ substantially, as well.
Deformed or malformed ears will require an altered selection of hearing aids, since these problems will affect retention and feedback during hearing aid usage. An extreme condition, such as the absence of the pinna, will alter the selection process by the dispensing professional since there may be no concha, canal, or both.
Another anatomical situation that can occur is the presence of a surgically treated ear that has a large irregular ear canal that may open wider once past the canal opening. Findings of this anatomical situation will require careful selection to avoid fitting complications. In recent years, completely in the canal (CIC) style hearing aids emphasize the need for observing canal configurations.
Adapting to hearing aids is a unique journey for everyone, and it is important to understand that this is a gradual process. The initial days or even weeks with hearing aids might involve an adjustment period as their auditory system gets accustomed to the amplified sounds. Patients may need time to adapt to their target amplification and may start with a lower level of sound as they adjust. Consistent use of the hearing aids is vital during this phase, as regular usage helps the brain adapt more effectively to the enhanced auditory input. It's common for wearers to notice a significant improvement in their ability to hear and understand speech, but also to experience new or heightened sounds initially.
Equally important are regular follow-up appointments with hearing care professionals. These appointments serve as checkpoints to monitor the patient's progress and address any emerging challenges. Hearing aids may need fine-tuning or adjustments based on individual experiences and feedback. Addressing concerns promptly not only enhances the effectiveness of the hearing aids but also fosters a sense of support and partnership between the client and the healthcare provider throughout the hearing aid journey. This ongoing communication helps in refining the hearing experience, making it a collaborative effort towards achieving the best possible outcomes for the individual's hearing health.
In addition to stating that a hearing aid fitting orientation should be device- and patient-centered, it should also state that the orientation needs to include discussion of use, care, and maintenance of the hearing aid(s) and accessories. This is where the device- and patient-centered aspects of the orientation come together to support the patient's success. It is important for clinicians to recognize that while the use, care, and maintenance aspect of hearing aids are straightforward to them, it needs to be explicitly discussed and demonstrated to patients.
Patients need to know the different parts of their hearing aids and the accessories to be able to effectively ask for what they need and advocate for themselves. On top of knowing the parts of the device, they need to know how to use them effectively. Patients need to be directed on the basics of hearing aids such as how to power them, batteries or charger, and how to insert them along with individualized instruction on usage. Audiologists are an integral part in showing and supporting proper use of hearing aids, as these are aspects that can be changed based on the programming.
Hearing aids come with instructions on the use of the devices, but these are generic and often cover various models from the manufacturer. While the booklet can support the discussion about the use of the device, it is impractical for a clinician to assume it has all of the information the patient will need to use the hearing aid effectively. These devices support various configurations that the audiologist programs based on what is appropriate for their patient. How the programming is set needs to happen in collaboration with the patient and how to access the different aspects of programming needs to be clearly explained by the audiologist. They need to know the difference between a short press and a long press, the function of the top versus the bottom of the rocker switch, and if the change will impact both hearing aids to list just a few different scenarios that a patient may encounter and be able to effectively manipulate.
Along with their hearing aids, many patients utilize accessories including smart phones to access apps and stream audio. While connectivity may have been considered a perk years ago, it is now becoming an integral part of hearing aid use for many patients. Audiologists need to be able to complete orientation on how hearing aids and smart phones interact. Showing patients the features of the manufacturer's app should also be a part of the orientation process. If the orientation process is viewed as an activity beyond the initial fitting appointment, these extension activities can be included. Individualized treatment will dictate if the patient should be oriented to the app at the initial fitting, during the acclimatization period, or if the patient will not utilize the app.
Hearing Aid Fitting Checklist
1. Comprehensive Hearing Assessment
Audiometric tests conducted
Type and degree of hearing loss determined
2. Selection of Hearing Aid
Recommendation based on assessment
Consideration of lifestyle and preferences
3. Customization and Programming
Adjustments for volume, frequency response, and features
Personalization with REM for optimal performance
4. Physical Fitting
Comfortable and secure fit
5. Instruction and Education
Instructions on insertion, removal, and maintenance
Guidance on daily care routines
Information on battery replacement
6. Adaptation Period
Encourage consistent use
Provide resources for troubleshooting
7. Follow-Up Appointments
Monitor progress
Make necessary adjustments