Non- Traditional Hearing Instrument Fittings Flashcards
Traditional
Hearing loss is similar in both ears and can accommodate “traditional hearing instruments”
Who is a candidate
- Severe to profound HL in one ear, normal hearing or aidable me loss in the other
- Severe to profound HL bilaterally
- Outer ear and middle ear deformities
- Conductive HL
- Significant asymmetrical losses
- Sudden sensorineural HL
Amplification options
- Cochlear implant bilaterally
- Cochlear implant in one ear, hearing instrument in the other
- Hybrid device (half cochlear implant and half hearing aid)
- CROS/BICROS (contralateral routing of signal)
- Bones anchored devices
- Middle ear implants
Info on cochlear implants
- surgically implanted (one ear at a time)
- designed for severe to profound sensorineural HL
- over 300,000 individuals worldwide have one
- CI centres in Toronto, London, and Ottawa
Components of a CI
Speech processor and microphone (BTE)
Transmitter (on head, looks like a wheel)
Receiver/ stimulator (in scalp, attached to transmitter)
Electrode array (furthest into cochlea)
CI candidates: infants/children
- bilateral severe to profound SNHL
- no contraindications
- have to wear HI for at least 6 months w a minimal benefit
- strong family support
- functioning auditory nerve
- desire to participate in an auditory/verbal society
CI candidates: adults
- good post lingual skills
- no contraindications for surgery
- realistic expectations
- participate in post surgery rehab
- longer the period of auditory deprivation, poorer the outcome
- functioning aud nerve
- acoustic neuromas
Controversy to CI
-threat to deaf culture and ASL
Hybrid CI
- part hearing instrument and part cochlear implant
- the electrode array is shorter (leaves low freq hair cells intact)
- appropriately for individuals w a moderate or better low freq HL, but profound high freq HL
Bimodal fitting
- hearing inst in one ear, CI in the other
- can be asymmetrical HL where each war can benefit from different technology
- many studies show that speech intelligibility, comfort and localization improve w Bimodal fittings vs. unilateral CI
Contralateral routing of signal (CROS)
- appropriate for individuals who have normal hearing on one side and no hearing on the other
- a mic w a transmitter (appearance of a hearing aid) would sit on the poorer ear
- receiver sits on the better ear, no mic
- signal wirelessly transmitted from poorer ear to better
CROS system benefits
- Head shadow effect
- impacts sound localization
- decreases high freq sounds - Improves SNR
- speaker (signal of interest) on the side w poorer hearing and noise on side w better hearing creates poor SNR, the CROS system is designed to alleviate that situation
Bilateral CROS (BiCROS)
- HL in one ear, u aidable loss in other
- signal would be a mixed between the hearing untrustworthy and CROS
- Mic in both hearing aids
- receiver in the hearing aid for the aides ear
- transmitted in unaidable ear
CROS vs. BiCROS
- both had transmitter in unaidable (poorer) ear
- reviewer w NO amplification would sit on the normal hearing aid in the CROS set up
- a traditional hearing instrument would sit on the aidable (better) ear in the BiCROS set up
Bone anchored devices
None anchored devices work on the following principle:
That hearing process = through ear canal, into middle ear, and vibrating fluid and hair cells in cochlea
Vibration of hair cells within cochlea can also be achieved by applying force directly to the skill (essentially the function of the middle ear system)
How BAHA implant system works
- Sound processor (external, captured sounds in mic and converts to vibrations)
- Abutment (transfers sound into mechanical vibrations from the sound processor to the implant)
- Titanium Implant (placed in the bone behind the ear, transfers sound vibration through the bone directly to the cochlea/ bypasses the outer and middle ear completely)
BAHA cntd. / further info on the procedure and the instrument itself
- day surgery, local anesthetic
- 3-4mm deep hole drilled, over time bone will grow around the abutment keeping it in place
- daily cleaning if surgical area required
- keep away from water
BAHA candidates
- constant discharge
- malformation of ossicles in the middle ear
- single sides deafness
- large air bone gap (>30dB)
- unilateral HL
Considerations if you get a BAHA
- infection and inflammation can occur around abutment
- failure to have bone formation
- no trauma of any kind to the head
- children must wait until they are at least three years old (adequate skill thickness)
Middle ear implants
- processor consists of: mic, amplifier, and battery
- signal sent to receiver through magnetic signal
- reliever produces an electrical signal down to the middle ear implant
- MEI is set against the round window of the cochlea where it’s able to vibrate the fluid within the inner ear
MEI candidates
- people unable to wear earmolds
- people w dysfunctional middle ear systems (cond HL)
- better high freq response, improves speech intellig. (Both in quiet and noise)
- no limitations in hot, dusty or wet environment
Complications of MEI
- operation has a lower success rate than that of BAHAs (partly due to the fact that the MEI has limited support, basically floats in the middle ear)
- issues w going through FMRI machines
- costly
Non traditional
Something other than a traditional hearing instrument is required in one or both ears
