1. Probe Tube Microphone Measurements (Basics and Definitions) Greg Nassar MCHAS Team University of Manchester

2. Prescriptive Targets Best Fit within Fitting Software Probe Tube Microphone Measures 2cc Coupler Targets Based on Pure Tones Kemar Different Input levels Individual ear canal size Individual ear canal acoustics Targets based on Speech

3. Probe tube Measurement microphone Reference microphone Supporting wire

4. Probe Tube Light Reflex Umbo

5. ULL HTL

8. Real Ear Unaided Response

9. Clinical measurement of Real Ear Unaided Response (REUR)

10. Real Ear Unaided Response 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.

11. Real Ear Unaided Response 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.

12. Real Ear Unaided Response Real Ear Aided Response 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. 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

13. Real Ear Aided Response Real Ear Unaided 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 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.

14. Real Ear Unaided Response 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 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.

15. Clinical measurement of real ear aided response (REAR)

17. Real Ear Unaided Response

20. Open Ear Gain

21. Insertion Gain

22. Open Ear Gain Insertion Gain Target Insertion Gain

23. Open Ear Gain Insertion Gain Target Insertion Gain The difference in dB as a function of frequency between the REUR and the REAR (REIR=REAR-REUR). The real ear insertion gain is the value in dB of the REIR at a specific frequency 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.

25. PTM’s 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 child’s eardrum will meet the requirements of the hearing impaired ear despite changes in resonant frequencies of the child’s ear canal over the first few years of life.

26. ULL HTL 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. 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.

27. 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