Verification Protocol

Goal: verified ear canal output matches frequency-specific targets from a validated prescriptive method; adjust frequency-specific MPO to optimize residual dynamic range and stay below loudness discomfort levels.
After individualized verification of gain/output, if fitting isn’t acceptable, minor deviations in gain/output may be necessary.

Navigate to AUDIOMETRY: enter age, select test transducer.
Enter BC data if A/B gap > 15 dB.
UCL: set to ENTER when LDL data available.
Set to AVERAGE unless measured NAL-NL2; always select ‘NO’ for DSL; set based on unilateral/bilateral fit.
Select prescriptive target; tonal vs. nontonal language.
Enter thresholds for at least 250, 500, 1k, 2k, 4k, 8k Hz.
Enter LDL data for frequencies assessed (example today: 105 dB HL for 500, 2k, 3k Hz).

REUR: Real-Ear Unaided Response (measure unaided canal output).
REOR: Real-Ear Ocluded/Aided Response (measure with device off, probe in canal).
Ensure cerumen isn’t blocking the tip; a flat pink-noise response indicates a clean probe.
Place marker 3–5 mm from the tympanic membrane (TM) to guide high-frequency output verification.
Insertion/removal and probe placement must be stable for accurate REUR/REOR results.

Do not move the black marker during REOR measurement; confirm it remains visible.
If the marker shifts, re-measure and re-reference.

Insertion loss: reduction in output due to the mass of the mold/dome.
Vent effect: from this point and below, REOR is no different than open ear canal.
Venting can alter low-frequency gain and overall audibility.

Vent effects can limit added gain at vented frequencies; venting may support or limit LF amplification depending on needs.
A dip in REOR may be due to vented vs retained gain transition; if the patient doesn’t perceive the dip, it may be acceptable to leave it.

Vent effect directly correlates with the SNR advantage provided by directional microphones.
Increased venting improves direct-signal audibility but reduces SNR benefit from directionality.

On-Ear Speech Map Assessment: measure REUR with SpeechMap, insert device and measure REOR with device off.
Do not document these results; overwrite as you proceed with the protocol.

In AUDIOMETRY, adjust:
- Age, HL transducer, UCL, RECD, language setting, and target type.
- Choose average NL2 targets or REDD as appropriate (binaural options available).
The differences between Threshold and LDL define the Dynamic Range:
- $DR = LDL - THR$
LTASS (Long-Term Average Speech Spectrum) and the speech envelope define audibility targets.

Speech envelope vs LTASS: crest factor around +12 dB and valleys around -18 dB for average conversational speech.
These lines bound the representative dynamic range of normal speech over a 10 s measurement.
Center line represents LTASS.

PRESCRIPTIVE TARGETS specify REIG (gain) or REAR (output) needed at each audiometric frequency.
Verification is checking that prescriptive gains/outputs are met; validation is confirming patient-perceived benefit.
Prescriptive target examples include 55-, 65-, and 75-dB input levels, plus MPO targets.

Contemporary options include:
- Proprietary manufacturer formulas.
- NAL-NL2 targets (Loudness equalization).
- DSL 5.0 (Loudness normalization).
- SII-based targets for audibility optimization.
DSL 5.0 and NAL-NL2 are common modern choices.

REAR shows the output of the speech envelope and aided audibility.
Green shaded area represents REAR for a 65 dB SPL input.
The difference between the gray (unaided) and green (aided) areas indicates the change in output due to the hearing aid.

First-fit algorithms automatically set initial gain/output, but REM often reveals mismatch to targets.
Don’t rely on first-fit; verify with REM to confirm actual output at the TM.
If REM shows mismatch, reprogram accordingly.

Objective: verify audibility of a moderately loud speech signal and maximize SII.
Task: Present a 65 dB SPL standardized SpeechMap signal.
Target Matching: adjust frequency-shaping bands across all input levels so that LTASS falls within +/− 5 dB of targets.
Steps: loop 65 dB SpeechMap input; highlight frequency ranges; raise/lower gain for soft, moderate, and loud as needed; avoid further LTASS changes once within tolerance; record LTASS after calibration sweep.

Compression shaping tuning aims to optimize detection of soft signals and comfort for loud signals.
Adjust only soft-input gain to shape a channel (soft gain) and then verify LTASS within ±5 dB of target.
Then adjust for loud input signals separately in a controlled LTASS measurement.
Repeat for 75 dB input when verifying loud-signal response.

Purpose: ensure tolerance to loud inputs.
Objective: set MPO about 5 dB under the patient’s LDL.
Use 85 dB SPL on-ear and 90 dB SPL in the test box for the assessment.
Check with patient: signal should be loud but acceptable or loud and uncomfortable; adjust MPO as needed.
Example setup: MPO shown as 85 dB in the protocol.

Simultaneous binaural verification using a two-ear verification system (e.g., Verifit 2).
Ensures consistent performance and cross-ear interaction.

Differentiate frequency shaping band adjustments from compression shaping channel adjustments and their uses during verification.
Analyze aided speech envelope features in relation to adjustments for soft and/or loud input signals during programming.
Be able to demonstrate the test protocol for programming/verification and interpret the measured findings: REUR, REOR, frequency shaping adjustments, compression shaping for soft and for loud input signals, and MPO adjustments.

Probe distance for high-frequency verification: approximately 3-5mm from the TM.
Pink-noise-based verification at 65dB SPL
LDL targets example: 105dB HL for specific frequencies.
Dynamic range concept: $DR = LDL - THR$ .
LTASS crest and valleys: crest = +12 dB, valleys = -18dB
Target LTASS tolerance during target matching: within >/=5dB of target
MPO planning: $MPO \,\approx\, LDL - 5\text{ dB}$ (example guidance).
Input levels used for prescription targets: $55\,\text{dB SPL},\ 65\,\text{dB SPL},\ 75\,\text{dB SPL}$ .
Verification goal: ensure verified output meets prescriptive targets before concluding fitting.