AC Hearing aids Flashcards
(40 cards)
Who is a candidate for hearing aids?
Anyone with a hearing loss that is impacting communication and/or daily activities.
Patient Centered Orientation
“Providing care that is respectful of and responsive to individual patient preferences, needs and values, and ensuring that patient values guide all clinical decisions”
Needs of each patient may be different
Don’t have to start with a blank slate for every patient
Audiologist is expert on hearing loss/hearing aids, but patient is an expert on their life and experience with hearing loss
Encourage open dialog
Top-down and Bottom up
What makes a good hearing aid candidate?
Someone who is motivated
Someone who needs help
A person with good word recognition
Useable hearing that can be aided
Limitations on profound hearing losses
Poor word recognition
Difficulties only under adverse listening conditions
Listening Devices and Related Technology
Assistive Listening Devices
Hearing Assistive Technology Systems (HATS)
Goals (of the technology):
Make speech audible
Restore range of loudness
Augment communication through nonauditory means
Enhance personal safety and environmental awareness
Usually used in conjunction with HAs
Hearing aids: Major trends
Miniaturization
Enhanced signal processing
Different kinds of signal processing and microphones
Noise reduction
A radio link connection between the left and right HA
Wireless technology
Smartphone interfacing
Hearing aid styles
Air conduction hearing aids
Bone conduction hearing aids
Used when patient’s can’t wear traditional amplification
Uses bone conduction
Implants
Digital Hearing aid components
Digital signal processing
Acoustic signal is converted to binary numbers and processed using algorithms
3 Main parts of a hearing aid
Microphone: picks up the acoustic signal -Converts it to an electrical signal
Amplifier: makes sound louder among other things
Receiver (speaker): Converts the processed electrical signal back to acoustic signal and passes it on to your ear
five key components
Microphone
Microchip
Amplifier
Battery
Reciever
Batteries
Batteries
Last for a few days to a few weeks
Disposable and rechargeable (newer)
Sizes: 10, 312, 13, 675
Microphones
Omnidirectional vs directional
Directional mics: enhance signal to noise ratio
Automatic directional systems: switch on their own based on environment
Improvement in hearing in background noise
Omnidirectional
As mentioned above, this microphone type has no directionality. “Omni” mics are used to pick up all or wide range audio. For example, they are used for choirs, when many instruments are played at once, or to pick up all audio on the stage.
Omnidirectional
All around you
Microphone directionality
Microphones have directionality that indicates from which direction they best pick up sound. Microphones that do not have any specific directionality (called “omnidirectional” microphones) will pick up sounds from all directions, thus sounds other than those of the intended instruments will go into the microphone. Particularly with PA systems, many instruments will often be played together on a stage, so it is necessary to have a good understanding of directionality. Some microphones have switches to select the preferred directional pattern.
Unidirectional
This type of microphone features directionality to the front only and is also known as “cardioid” (because of its heart shaped directional pattern). Cardioid mics are most often used with PA systems for vocals, instruments, etc. In the diagram, 0°indicates the front of the microphone.
Directional
Directional
Only in front of you, perceiving the things directly in front of you
Biggest jump in improvement over the last twenty years has been in Microphones
Used to have omnidirectional microphones – 360 degree microphones
Directional microphones – two microphones, they can figure out by timing and intensity differences what sound is coming from the front and the back
For directionality purposes you need to have the space to put two microphones
Bidirectional
This type of microphone features directionality to the front and rear. Because bidirectional microphones will also pick up audio to the rear, they are rarely used with PA systems. They are often used to record audio between two people who are face to face, such as during radio interviews.
Amplifier
Gain: Amount of amplification provided
Noise reduction
Wind reduction
Wide dynamic range compression
Peak-clipping
A DISTORTION caused when the GAIN of an amplifier is increased to a point where the high points, orpeaks, of the SIGNAL or WAVEFORM are cut off at a level where the amplifying circuits are driven beyond their overload point.
Gain saturates at a certain level
Peak-clips which limits level of audio signal
Introduces distortion
Compression
Goals:
Limit the maximum output of hearing aid so patient is never uncomfortable
Provide a range of sounds within a persons dynamic range (soft, average, loud sounds)
Provide a varying amount of gain as a function of the input level (if someone is whispering add more gain, if sound is too loud compress)
May be linear up until a certain point (kneepoint) then change into compression
Kneepoint (point where linear amplification changes to compression)
Attack and release times
Receivers
Creates an enhanced soundwave.
Convert the signal sent from the processor to audible acoustic sounds.
It is placed directly in the ear canal or connect to a small tube that’s inserted into the ear.
Other features
ON/OFF
Typically just battery door open vs battery door closed
May be an on/off switch
May be on VC wheel
Telecoil
Induction coil within hearing aid
Used for telephone (land lines) or public loop systems
Electromagnetic: bypasses HA microphone
Not on all hearing aids
Minimize feedback
Can be automatic t-coil on some newer HA’s
Volume Control
User can adjust level of amplification
Can be a wheel, a toggle switch, or done on a remote or smart phone
Audiologist can disable this feature or limit the range
Program button
Multiple memories
Customize programs
Small button on hearing aid
Can be disabled/enabled by audiologist on the software
Remote Control
Can change programs
Change volume
