On Ear / Real Ear Procedures
- Calibrate the probe tube
- Otoscopy
- Check placement of the speaker
- Place the probe tube
- Measure the probe tube and mark
- Adult: 30mm males, 28mm females, kids 20-25mm
- Measure the probe tube and mark
- Geometric
- Measure 5mm past tip of ear hold or hearing aid
- Closer to the TM the MORE accurate the high frequencies
RECD - Real Ear to Coupler Difference
- ANSI Definition: Difference in dB as a function of frequency between the SPL at a specified measurement point in the ear canal and the SPL in a 2cc coupler for a specified input signal
- usually a positive number
- smaller heads = larger RECD
- what if RECD is negative?
- Know the levels of amplified sound delivered into the patient's ear canal
- accounts for unique acoustic properties of the ear and earmold coupling (if the RECD is conducted with the earmold)
- this helps avoid errors that can occur when using average values in the fitting process
- hearing instrument response shaping can be performed in the hearing aid test chamber, under highly controlled acoustic conditions
- the degree of cooperation and amount of time required from the patient in the fitting process is greatly reduced
REUR/REUG
REAR/REAG - Real Ear Aided Response / Gain
- Difference in dB as a function of frequency between the SPL at a specified measurement point in the ear canal and the SPL at the field reference point for a specified sound field, with the hearing aid (and its acoustic coupling) in place and turned on
- Why?
- prescriptive methods specify REAR/REAG targets for a variety of input levels and thus require these measurements during the fitting process
- used as a reference for calculation of real ear insertion gain (REIG)(i.e. REAG - REUG = REIG)
- an individual's auditory characteristics are specified in dB SPL
REIG - Real Ear Insertion Gain
- ANSI Definition: Difference in dB as a function of frequency between the REAG and the REUG obtained with the same measurement point and the same sound field conditions. Previously called real-ear insertion response
- Why?
- Determine whether a particular hearing aid setting has achieved a particular insertion gain prescriptive target
- in the absence of a theoretical target, the calculation of REIG becomes rather meaningless
REOR/REOG
Probe microphone measures allow you to account for RECD and/or REUR
- RECD makes sense whenever you are dealing with couplers and want to be exact and/or know that your patient is very different from a coupler
- REUR makes sense when you need to have a reference for insertion gain or when all you have is sound field thresholds
Challenges for the Clinician
- Measure SPL at the eardrum
- Choose a valid, reliable outcome measure
- Remember: feedback, occlusion problems and loudness comfort are still the top three reasons for individuals rejecting hearing aids
- Batteries and moisture continue to be a problem for patients
- Re-structure your time so customization is part of your activities
- Embrace new developments while following an evidence based approach
- Provide the rehabilitation that makes the person an active participant
- Include hearing protection in everything you do!