Efficacy of a Coupler-Based Hearing-Aid Fitting Approach for Experienced Users
Phase: NA
Conditions: Hearing Loss
Sponsor: VA Office of Research and Development

Study Title:  Coupler-Based Hearing-Aid Fitting Approach for Experienced Users 
NCT02772757 
ID: C1895-P 
Principal Investigator: Sherri L. Smith, Au.D., Ph.D. 
April 30, 2015 
 
 

The purpose of this study is to evaluate procedures designed to greatly improve the efficiency 
of hearing-aid delivery to experienced hearing-aid wearers. Specifically, the fitting accuracy and 
patient experience for two approaches that would not require additional direct patient contact will 
be compared to the current standard-of-care (SoC) approach in which in situ real-ear aided 
responses (REARs) measures are obtained. The proposed approaches use derived REAR 
hearing-aid fittings based on either (1) average-corrected or (2) individually-measured real-ear to 
coupler differences (RECDs) for fitting and verification of replacement amplification. The primary 
research aims are to determine: 
1. if the in situ REARs differ from the derived REARs in the experimental groups and if the 
derived REARs in the experimental groups differ from the in situ REARs in the SoC group,   
2. if fittings based on measured versus average-corrected RECD values differ in the 
experimental groups, and 
3. if the subjective hearing-aid outcomes differ among the groups. 
 
RESEARCH DESIGN AND METHODS 
Design.  A mixed model, repeated measure design will be used in the current study.  
 
Participants. There will be three groups of participants.  One group will serve as the active-control 
group and will receive the standard-of care 30-min appointment (SoC group). One experimental 
group will have the average-corrected (for venting) RECD (Exp-AVGc Group) incorporated during 
the RECD-based verification and the other experimental group will have the measured (with 
custom earmold) RECD (Exp-M Group) incorporated during verification. The two experimental 
groups will be mailed their replacement hearing aids after they are programmed and verified with 
RECD-based fittings. The participants will be randomly assigned to each group.  
 
Inclusion Criteria: Participants will be included in the study if the following criteria are met: 
• 
experienced BTE hearing-aid users who are obtaining replacement VA-issued BTE hearing 
aids coupled to a custom earmold that is simply an upgrade in model (e.g., 2010 Phonak Exeila 
211 Art BTE upgrading to a 2014 Phonak Bolero Q90 BTE) with the same style earmold  
• 
no more than a moderate sensorineural hearing loss (defined as < 60 dB HL pure-tone average 
at 500, 1000, and 2000 Hz AU) 
• 
ability to read and write in English as determined by reading a few sentences from the consent 
document aloud so that self-report measures can be completed 
 
Exclusion Criteria: Participants will be excluded if any of the following criteria are true: 
• 
outer or middle ear pathology as determined by otoscopy, immittance, and/or audiometric 
testing (e.g., conductive or mixed losses) 
• 
lack of phone or non-use of the phone as the participants will be required to conduct a 
telephone interview after they obtain their replacement hearing aids  
• 
unwilling or unable to be mailed hearing aids 
• 
co-morbid condition that would preclude their participation as determined by a chart review 
(e.g., dementia, visual impairment/legal blindeness, substance abuse, etc.)  
 
Materials/Tests: 
In addition to RECD and REAR measures, this study will include measures of speech-in-noise 
abilities and hearing-aid outcomes. These measures are described below:   
Client-Oriented Scale of Improvement (COSI; Dillon, James, & Ginis, 1997). The listener 
nominates up to five listening goals on the COSI.  After hearing-aid use, the listener assesses two 
outcomes for each goal. One outcome is the “degree of change” relative to the patient’s unaided 
experience. Responses are recorded on a categorical scale from ‘worse’ to ‘much better.’  The 
second outcome is the final satisfactory “aided” ability for each goal as measured on a categorical 
scale from hardy ever (10%) to almost always (95%).  The percentage of ‘better’ and ‘much better’ 
responses and the average of the final ability will be calculated across goals. (Session 1—goals 
established and Session 3—outcomes established—See Procedure Section below) (5 minutes).       

Device Oriented Subjective Outcome (DOSO) Scale (Cox, Alexander, & Xu, 2009). The 
questionnaire is comprised of 28 items making up the following six subscales related to listening 
performance with hearing aids: (1) speech cues, (2) listening effort, (3) pleasantness,(4) quietness, 
(5) convenience, and (6) use. Responses from ‘not at all’ (1 point) to tremendously (7 points) are 
recorded for each item. Higher scores represent better device-oriented subjective outcome. This is 
a post-only measure (Session 3) (10 minutes). 
Satisfaction with Amplification in Daily Life (SADL) (Cox and Alexander, 1999). The SADL 
questionnaire has 15 items that examine self-reported hearing-aid satisfaction.  The following four 
subscales are included: (1) positive effect, (2) negative features, (3) personal image, and (4) 
service and cost. For the current study, item 14 on the service and cost subscale was not used as 
the Veterans were not charged for the cost of their bilateral hearing aids.  The SADL uses a 7-item 
response scale in 1-unit steps, 1 (poorest) to 7 (highest) for each item, which are averaged for 
each subscale and total scale score. (Session 3) (5 minutes).   
Words-In-Noise (WIN) test uses the NU-6 materials in a six-talker multi-talker babble.  The 
words are presented at 7 signal-to-noise ratios (S/N), 24-dB to 0-dB S/N, in 4-dB decrements.  The 
noise level remains constant and the level of the words varies. Listeners with pure-tone averages 
≤25-dB HL will be presented with noise levels at 70-dB SPL and the words will vary from 94- to 70-
dB SPL. Listeners with pure-tone averages 25.1- to 40-dB HL will be presented with noise levels at 
80-dB SPL and the words will vary from 104- to 80-dB SPL. Listeners with pure-tone averages 
between 40.1- and 60-dB HL will be presented with noise levels at 90-dB SPL and the words will 
vary from 114- to 90-dB SPL (following Wilson, 2003; Wilson, Abrams, & Pillon, 2003; Wilson & 
Burks, 2005). The 50% point on the WIN will be calculated for each ear using the Spearman-
Kärber equation (Finney, 1952) in addition to the percent correct performance at each signal-to-
noise ratio. (Session 1) (5 minutes). 
 
Procedures. 
Session 1 (Baseline, Pre-Fitting). All testing will be completed separately in each ear for all groups. 
Otoscopy will be performed and cerumen management completed as needed. The standard 
audiometric evaluation including air- and bone-conduction pure-tone audiometry; word-recognition 
in quiet (NU-6 words) and in noise (WIN) will be completed. Tympanometry and aural acoustic 
reflexes also will be measured. The COSI will be completed to obtain the listening goals of the 
participant and to facilitate programming needs of the replacement hearing aids (e.g., whether or 
not manual programs are needed/desired). In addition, an intake form (Appendix 2) will be 
completed for all groups to determine other device options and function (e.g., volume control 
options such as yes/no or unlinked/linked; removal filament or not; earmold style from previous 
order form; and tubing length; etc.). If care or use questions arise based on responses on the 
intake form, then they will be answered during this session. The replacement hearing aids and 
earmolds will be ordered using the earmold scans on file with the manufacturer provided that the 
current earmolds from the old hearing aid are a good fit. If not, then ear impressions will be made 
for replacement earmolds. 
For the experimental groups, the tubing length of the current earmolds will be measured 
carefully so that the replacement earmold tubing can be cut to the same length at the RECD-fitting 
(Session 2-below). For the Exp-AVGc group, the current earmold vent size will be measured if the 
actual size is not available on the previous order form.  That way, the average RECD values can 
be corrected for the vent size of the earmold at the RECD-fitting (Session 2).  
For the Exp-M group only, RECD values will be obtained separately for each ear with the 
patient’s current earmolds after they have been cleaned and tubing changed as needed. Using the 
current earmold as opposed to the foam insert will allow venting and tubing characteristics to be 
incorporated in the RECD-fitting. The RECD measurement protocol will follow the standard clinical 
protocol and will use the Verifit 2 system. The test box reference microphone will be calibrated. The 
RECD transducer will be placed on the BTE coupler and the coupler response will be obtained. 
The probe tube will be inserted 25-27 mm from the antitragal notch in order to ensure placement 

within approximately 2-5 mm from the eardrum. The participant’s current earmold (lubricated to 
ensure a good seal) will be placed in the ear canal and care will be taken not move the probe tube 
during earmold insertion. The RECD transducer will be coupled to the earmold tubing and the real-
ear response will be obtained. The difference between the coupler and real-ear responses is the 
measured RECD.     
 
Session 2: The Intervention ‘Visit’.   
SoC Group Fitting. This group will receive the SoC, 30-minute face-to-face fitting appointment 
4-6 weeks after Session 1, the average wait time for a fitting appointment. The right and left 
hearing aids will be programmed separately to the National Acoustics Laboratory Non-Linear 2 
(NAL-NL2) prescription.  The REAR of the hearing aids will be verified to the 50-, 65-, and 75-dB 
SPL prescriptive targets generated by the Verfit 2 system using the speechmap stimulus. The 
criterion for an appropriate fitting would be ± 3 dB between the output and the prescriptive target 
from 250 Hz to the frequency in which the unaided threshold crossed the 65-dB SPL target.  The 
Real Ear Saturation Response (RESR) will be measured using an 85-dB swept pure-tone to 
ensure that the maximum output of the hearing aids does not exceed the predicted uncomfortable 
loudness levels of the participant. The programming options will be optimized based on the 
information obtained on the intake form (Appendix 2). The participant will be provided with the 
manufacturer brochure, programming report from the manufacturer software, and the VA Hearing 
Aid Booklet. Consistent with current SoC, no orientation will be provided.  
Experimental Group Fittings. The participants in the experimental groups will not be present 
during the fitting. The hearing aids will be fitted in a manner similar to the SoC fitting except the 
average-corrected (for vent size) RECD (Exp-AVGc Group) or measured RECD from Session 1 
(Exp-M group) will be inputted into the Verfit 2 to generate the prescriptive targets and the derived 
REARs will be obtained following the standard clinical procedure. In short, the tubing of the 
replacement earmold will be cut to length and coupled to each hearing aid. The earmold will be 
attached to the HA-1 coupler with putty ensuring that the eartip is flush against the opening of 
coupler and the vent sealed, as is standard with this procedure. The hearing aids will be 
programmed and the derived REARs will be obtained and verified against the prescription. After 
programming and verification, the hearing aids will be mailed to the patient along with the 
manufacturer brochure, programming report from the manufacturer software, and the VA Hearing 
Aid Booklet within one business day of their receipt from the manufacturer. It is estimated that 
these experimental fittings will take 15 minutes, or half the time of the SoC fittings.  A signature will 
be required to accept the delivery and the delivery will be tracked.    
 
Two-Day Follow-Up Phone Call.  All participants will receive a 2-day follow-up phone call after the 
hearing-aid fitting.  The experimental groups will be phoned after delivery of the hearing aid is 
confirmed with the delivery receipt.  A telephone script (Appendix 2) will be used to ask questions 
about the physical comfort of the device, sound quality, and any other hearing-aid problems or 
questions.  
 
Session 3 (One-Month Post-Fitting). One month after the hearing-aid fitting, all groups will return to 
complete subjective outcome measures.  The measures will be presented in random order. The 
COSI outcomes will be measured to determine if the hearing aids are meeting the patient-
nominated goals. The SADL will be completed and the Service and Cost subscale will be of great 
interest due to the service-related items that may differentiate between groups.  The DOSO will be 
used as it assesses hearing-aid outcomes in six domains. An exit survey (Appendix 2) also will be 
administered to gain insight into the perceptions related to service delivery, access, and 
convenience. In addition, in situ REARs will be obtained from all groups using the current 
programming from the replacement aids. These in situ REARs will allow within and between group 
comparisons regarding the hearing-aid function and determine the accuracy of the experimental 
fittings relative to the SoC fittings. The repeat in situ REAR measurements in the SoC group (i.e., 
Sessions 2 and 3) will serve to assess the inherent variability with in situ REAR measurements and 

will facilitate interpretation of REAR data when comparing the accuracy of the in situ and derived 
REARs in the experimental groups.        
 
Attrition.  In our experience (Smith and Ricketts) with a multi-session (4 sessions over 6 months), 
hearing-aid clinical trial, we had a low local attrition rate of 8.7%.  The primary reasons for 
withdrawal were due to personal reasons which included illness, moving out of state, and 
transportation issues during inclement weather (i.e., snow). Thus, we considered a conservative 
estimate of 15% attrition for the proposed multi-session study. 
 
Sample Size. Based on an expectation that REAR measurements should be within 2 dB on 
average across frequency, and an SD of 2, then 18 participants are needed for each group (total N 
= 54) assuming a power of at least β = .80 and p = .05.  Considering 15% attrition, then 9 
additional subjects will be needed (N = 63) resulting in 21 participants per group.  Participants will 
be recruited from the Mountain Home VA audiology clinics. Last year, our clinic served 7,481 
Veterans during 16,278 patient visits and dispensed 7,134 hearing aids. Also, based on the 
national average, it is estimated that ~50% of VA hearing aids dispensed are replacement hearing 
aids for experienced users. Thus, we anticipate no difficulty in recruiting the target sample at 
Mountain Home.  
 
Data Analysis.  
Specific Aim 1 and 2. A mixed-model analysis of variance (ANOVA) will be conducted. This 
analysis will examine differences (in dB SPL) for REAR (actual vs derived using average vs 
measured RECD) across frequency and ears within and between the groups.  This analysis will 
determine (1) if the in situ REARs differ from the derived REARs in the experimental groups and if 
the derived REARs in the experimental groups differ from the in situ REARs in the SoC group (2) if 
coupler-derived REARs using average-corrected or measured RECDs differ; and (3) if the 
average-corrected RECD differs from the measured RECD.   
 
Specific Aim 3. A multivariate ANOVA will be conducted to examine group differences among the 
outcome measure subscales. A logistic regression also will be conducted to examine if the 
proportion of responses differ among the groups on the specific telephone and exit survey items of 
interest.