Amplification - Special Features Flashcards
What are 5 special features that can be used in HAs?
1) telecoils
2) directional microphones
3) direct audio input
4) special amplifiers
5) noise reduction circuitry
What are telecoils?
A small induction coil which changes electromagnetic energy into electrical energy
How are telecoils use?
Telephone receivers emit an electromagnetic signal and the telecoil in the HA can pick up the signal, essentially replacing the mic
Why is using a telecoil for phone calls better than just holding the phone up and using the HA mic? (2)
- the HA mic with a phone can cause feedback
- it only amplifies the phone call signal, not any background noise
When telecoils were first used in HAs, it was _____, then phone design improved but the _______ wasn’t as strong. So since _____, the FCC has required what?
Good
Signal
1989
That all phones sold in the US be HA compatible
The FCC requirement for phone HA compatibility didnt include what which led to what issue? But why is this not really a problem?
Cell phones, so not all cells are compatible
But most HA user benefit from /use Bluetooth more
How does an HA user activate the telecoil? (2 ways)
With a switch with the options M, T, or MT (and there are also automatic telecoils that sense electromagnetic fields and automatically activates)
What are the 3 options on an HA for telecoil settings?
M: mic
T: telecoil
MT: both
Originally telecoils were designed for what but now they are widely used for what?
Phone
Couple HAs with assistive listening devices
If a person has/uses an ALD they should purchase an HA that has what?
Strong and reliable telecoils
What is one special feature of HAs that you almost always want?
Directional microphones
What are the 3 possibilities for HA mics?
1) directional
2) omnidirectional
3) both
What are directional microphones?
More sensitive to sounds coming from a particular direction
What are omnidirectional microphones?
Approximately equally sensitive to sounds coming from all sides
What types of HAs are directional mics available for?
BTEs and ITEs (larger)
What is the benefit of directional mics?
significantly enhance SNR, and therefore improve speech understanding
Where do directional mics lose some of their effectiveness?
Reverberant environments
How are directional microphones turned on and off?
- manual option
- automatic switch based on listening environment
- most advanced “focus” the mic based on where speech is occurring
What is Direct Audio Input?
Means of delivering an electrical signal directly to an HA by means of a snap-on “boot” or “shoe” that established an electrical connection to the HA
DAI is typically only available in _____, and is widely used for what?
BTEs
Couple assistive listening devices to an HA
Which 3 types of HAs require a seperate piece, and what is is?
1) BTE
2) body
3) eyeglass
Earmold
What is the function of an earmold?
Direct amplified sound toward the TM in a way that prevents feedback
The selection of earmold styles is based on what 3 things?
1) feedback prevention properties
2) client comfort
3) cosmetic preferences
Why do we (almost) always use earmolds with children?
More secure and durable
And there are fun styles!
What are possibilities for earmold materials?
- hard acrylics to softer/pliable
- hypoallergenic
What material is typically used for children’s earmolds? Why?
Soft materials because they dont need to be replaced as often
How does the earmold affect acoustics?
It modifies or “tunes” the HA response
