How does NAL-NL prescribe maximum output?
What does NAL software prescribe?
How does NAL-NL prescribe compression?
What’s different in NAL-NL2?
DSL v 5.0 goals
DSL v 5.0 features
DSL for Children
DSL v 5 stages:
(1) Expansion
(2) linear gain
(3) compression
(4) output limiting
Hearing Aid Verification (Purposes of Real-Ear)
Speaker Location
Speaker distance from patient: Should be close enough to receive a strong sound level at the ear without speaker overdrive, and reduce influence of other noises in the room.
Fonix 7000: 45 degree azimuth, 12” away from patient
Audioscan Verifit: 0 degree azimuth, 18-36” away from patient.
What types of signals can you use for real-ear testing?
Use speech or speech-like signals or disable digital noise reduction – otherwise the hearing aid will interpret the test signal as noise and attempt to reduce gain.
REUR
Real Ear Unaided Response
The SPL, as a function of frequency, at a specified point in the un-occluded ear canal for a specified sound field. Can be expressed in dB SPL, or as gain (dB) relative to the stimulus level
REOR
Real EAr Occluded Response
- The SPL, as a function of frequency, at a specified point in the ear canal for a specified soundfield, with the hearing aid in place and turned off. Expressed in dB SPL or as gain (dB) relative to the stimulus level
REAR
Real Ear Aided Response
- The SPL, as a function of frequency, at a specified measurement point in the ear canal for a specified soundfiled, with the hearing aid in place and turned on. Expressed in dB SPL or (less commonly) as gain (dB) relative to stimulus level
RESR
Real Ear Saturation Response
The SPL, as a function of frequency, at a specified measurement point in the ear canal with the hearing aid in place and turn on. Stimulus level is intense enough to operate the hearing aid at maximum output (typically 90 dB SPL)
REIR
Real ear insertion response
The difference, in dB as a function of frequency, between the REUR and the REAR measurement taken at the same measurement point in the same soundfield
What is REAR minus REUR?
If expressed as gain relative to stimulus level, you may see REAG or REUG. REIG is always “gain” relative to unaided response.
What levels do you test REARs?
60
70
80
Why do we do REAR measures?
accounts for the aid (including earmold effects, like venting) and the ear/head. It realls to the sound level at the patient’s TM, regarless of what influences that sound level (ear or aid). It is easy to consider in terms of dynamic range/audibility
REIG
REIG = REAG - REUG
REIG tells you what the patient is getting with the hearing aid that they didn’t have before.
Requires you measure an inidividual REUR (or you can use average REURs, but they won’t account for your patient’s individual ear canal effects)
Which to use, REIR or REAR?
•
REIR (has fallen out of favor among clinicians):
–
Tells you what the patient is getting with the hearing aid that they didn’t have before
–
Requires you measure an individual REUR (or you can use average REURs, but they won’t account for your patient’s individual ear canal effects)
•
REAR:
–
Just tells you the sound level at the patient’s TM. Doesn’t care where gain comes from (ear or aid)
–
Easier to consider in terms of dynamic range (threshold to UCLs) to assess audibility
What is important while measuring RESR levels?
Be sure the RESR is not exceeding LDL levels – make any necessary MPO adjustments. Remember general complaints of “loudness” may be the MPO, or perception of lower levels
RECD
The RECD procedure consists of: (1) a 2cc coupler-based measurement and (2) a real-ear measurement. The 2cc coupler measurement is made on the same coupler used for hearing aid fitting. A transducer from the real-ear system delivers a signal into the coupler and defines the SPL of the signal as a function of frequency. Most probe-microphone systems have the capability to permanently store the coupler response
The same signal is delivered from the same transducer into the ear via a custom earmold or foam tip. The system again measures the level of the signal (this time in the ear) as a function of frequency. The difference between the signal on the ear and the coupler is the real-ear-to-coupler difference.
Instead of using the signal from the real ear system, you can measure RECD with an audiometer and insert phone (shown here) or with the same hearing aid, same earmold, same settings. The only requirement is that the sound source be exactly the same for both coupler and in-ear measures.
Potential problems doing real ear with open fits