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)