Probe Tube Microphone Measurements

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Probe Tube Microphone Measurements (Basics and
Definitions) Greg Nassar MCHAS
Team University of Manchester
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Prescriptive Targets
Probe Tube Microphone Measures
Best Fit within Fitting Software
2cc Coupler
Individual ear canal size
Individual ear canal acoustics
Kemar
Targets Based on Pure Tones
Targets based on Speech
Different Input levels
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Probe tube
Measurement microphone
Reference microphone
Supporting wire
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ULL
HTL
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Real Ear Unaided Response
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Clinical measurement of Real Ear Unaided Response
(REUR)
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REUR The SPL as a function of frequency in
the unoccluded ear canal. Is expressed as either
SPL or gain in dB relative to the stimulus level.
Real Ear Unaided Response
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REUR The SPL as a function of frequency in
the unoccluded ear canal. Is expressed as either
SPL or gain in dB relative to the stimulus level.
Real Ear Unaided Response
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REUR The SPL as a function of frequency in
the unoccluded ear canal. Is expressed as either
SPL or gain in dB relative to the stimulus level.
Real Ear Aided Response
REAR The SPL as a function of frequency in
the ear canal with the hearing aid in place and
turned on. Also known as in situ response and is
normally displayed as dB SPL
Real Ear Unaided Response
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REUR The SPL as a function of frequency in
the unoccluded ear canal. Is expressed as either
SPL or gain in dB relative to the stimulus level.
Real Ear Aided Response
REAR The SPL as a function of frequency
in the ear canal with the hearing aid in place
and turned on. Also known as in situ response and
is normally displayed as dB SPL
Real Ear Unaided Response
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REUR The SPL as a function of frequency in
the unoccluded ear canal. Is expressed as either
SPL or gain in dB relative to the stimulus level.
Real Ear Aided Response
REAR The SPL as a function of frequency
in the ear canal with the hearing aid in place
and turned on. Also known as in situ response and
is normally displayed as dB SPL
Insertion Gain
Real Ear Unaided Response
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Clinical measurement of real ear aided response
(REAR)
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Real Ear Unaided Response
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Open Ear Gain
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Insertion Gain
Open Ear Gain
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Insertion Gain
Target Insertion Gain
Open Ear Gain
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In adults the REIR is the measure of choice in
verifying the electroacoustic characteristics of
the chosen hearing aid meet the prescribed gain
and desired frequency response.
Insertion Gain
Target Insertion Gain
The difference in dB as a function of frequency
between the REUR and the REAR (REIRREAR-REUR). Th
e real ear insertion gain is the value in dB of
the REIR at a specific frequency
Open Ear Gain
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PTMs on Children REAR should be used rather
than REIR. The REAR will prescribe the same gain
at the eardrum for a given hearing loss,
regardless of ear canal size and shape. This
ensures target speech levels at the childs
eardrum will meet the requirements of the hearing
impaired ear despite changes in resonant
frequencies of the childs ear canal over the
first few years of life.
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RESR Is the SPL as a function of frequency in
the ear canal with the hearing aid in place and
turned on. The measurement is obtained with the
stimulus level sufficiently intense as to operate
the hearing aid at its maximum output level.
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RECD Is the difference in dB as a function
of frequency between the outputs of a hearing aid
measured in the real ear versus a 2cc
coupler. Using these measurements the real ear
performance of the hearing aid can be predicted.
HTL
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Key Points to Take Away!
REIG target based upon the average adult ear
canal resonance
Not appropriate to ear canal with different
acoustic properties to average adult ear
REAR target based upon the desired SPL at the
eardrum
This is always the same for a given hearing
threshold (dB SPL) regardless of the size of the
ear canal.. However the output of the hearing
aid still needs to be corrected for differing ear
canal sizes