Characterizing Variability in Hearing Aid Outcomes Among Older Adults
Phase: NA
Conditions: Hearing Loss, Presbycusis
Sponsor: Northwestern University

Variability In Hearing Aid Outcomes In Older Adults 
    
NCT02448706
9.1.2019

HA outcomes in Older Adults: 
Inclusion and Exclusion Criteria 
All individuals will receive a hearing test to determine their current hearing status. Additionally 
cognitive testing may be administered to determine inclusion, as described below. 
Inclusion criteria: 
Experimental group: Adults aged 55 or older with sensorineural hearing loss.  
 
Exclusion criteria: 
Diagnosis of dementia; failure to pass the cognitive screening measures; conductive hearing loss; 
hearing loss exceeding the limits that can be successfully aided with hearing aids (i.e., profound 
hearing loss); hearing loss remediated with a cochlear implant (cannot wear hearing aids), and 
Non-English speaking participants. Additionally participants must be free from clinically 
significant unstable or progressive medical conditions, or conditions which, in the opinion of the 
investigator places the participant at unacceptable risk if he or she were to participate in the 
study.   
 
Procedures Involved 
 
Participants.  We will include only older listeners with adult-onset hearing loss.  Because this 
experiment requires that listeners be fit with binaural hearing aids, all participants’ hearing loss will be 
mild to moderately severe and symmetrical (<15 dB average difference between ears, at .5, 1, 2, 3 
kHz).normal-hearing adults will not be included.  All participants will be in good health (self-report), 
have no significant history of otologic or neurologic disorders and speak English as their primary 
language.  To ensure they can read computer displays, all participants will have good organic or 
corrected visual acuity.   Only participants who are not actively wearing hearing aids during the past 
year will be included.  This avoids any bias from previous hearing aid experience and ensures that the 
participant will be using only the study hearing aids.  Participants will be divided into low and high 
working groups based upon the results of their working memory reading span tests. Once either high or 
low working memory group is filled (approximately 25 participants each) we will selectively enroll 
participants to fill the other category.  
 
The following tests will be completed for all participants and will used to determine study eligibility as 
well as group assignment.  Audiogram (PTA1) will be considered in the analysis.  The remaining tests 
are included to describe the subject cohort and as possible covariates.   
 
1. 
Case history and otoscopic exam 
2. 
Audiogram (pure-tone air and bone conduction thresholds).   
3. 
Loudness discomfort levels.  LDLs will be measured at .5 and 3 kHz and used in combination 
with subject report to ensure that stimulus levels are not uncomfortable.     
4. 
Tympanometry.  Subjects with conductive loss (air-bone gaps > 10 dB at any frequency and/or 
abnormal immittance will be excluded from participation.   
                                                 
1 Pure-tone average.  We expect to use standard PTA (.5, 1, 2 kHz) and high-frequency PTA (2, 3, 4 kHz) as possible 
covariates.   

HA outcomes in Older Adults: 
5. 
Monosyllabic word recognition in quiet.  Although of limited experimental use, this is included 
to facilitate comparisons to other published research 
6. 
QuickSIN.  This 5-minute recording contains female-talker sentences in a background of 4-talker 
babble. The speech is audible and the noise is gradually increased. The final score is based on 
number of words correct and expressed as a threshold in dB SNR.  A larger SNR indicates 
poorer ability to hear in noise. 
7. 
Cognitive testing.  Working memory is a limited-capacity system that enables an individual to 
actively maintain task-related information while simultaneously performing other relevant 
processing. In contrast to short-term memory, which emphasizes pure storage capacity, working 
memory is conceptualized as an active system whose storage mechanisms operate in the service 
of complex goal-directed cognition (e.g., language comprehension, mental arithmetic). 
Numerous studies have shown that performance on working memory tasks can predict individual 
differences in complex cognitive activities better than pure-storage measures such as digit span. 
Recent data suggests that working memory capacity, as measured by the reading span test, can 
predict benefit of hearing-aid processing. We will use a complex verbal span task, a measure of 
working memory capacity developed to capture the individual variability in such capacity to 
coordinate simultaneous storage and processing requirements. Participants read a series of 
sentences presented a few words at a time on a computer monitor and then recall the last word of 
each sentence.  
 
Hearing aid fitting 
 
 We will select two sets of signal processing parameters that either provide a high level of signal 
manipulation (with concomitant improved audibility) (Fitting A) or a low level of signal manipulation 
(Fitting B).  We will select signal processing (combinations of WDRC, frequency compression) that 
produce either high levels of signal manipulation or low levels of signal manipulation; that is, that 
represents a situation of more or less signal manipulation, with corresponding variability in patient 
response.  Note that our goal here is simply to select processing choices that suit the experimental 
hypothesis; we are not interested in making recommendations about specific algorithm parameters (e.g., 
frequency compression); rather, we are interested in testing the idea that listeners respond differently to 
the net effect of signal manipulation and that those responses are related to patient factors including 
cognition.  All hearing aid parameters will be constrained such that the signal is audible, comfortable, 
and clinically realistic (based on the range of available fitting parameters). 
 
We will obtain hearing aids for use in the trial.  We will choose the specific hearing aids based on the 
technology available at the time of the trial.  Commercial hearing aids universally offer noise 
suppression and WDRC.  We anticipate that twelve individuals (fit binaurally = 24 aids, with 4 aids held 
for backup) will be enrolled at a time.  Each individual will wear one processing condition for 6 weeks, 
followed by the other for 6 weeks, for a total 12-week trial.  Order of the processing conditions will be 
counterbalanced across subjects.  Allowing for transition time (to order earmolds, program hearing aids, 
etc.) we anticipate testing 36 individuals per year and completing the target sample of 45 subjects in 
<1.5 years.  Fitting procedure will follow accepted clinical protocol.  Briefly, we will program each 
hearing aid to NAL-NL frequency-gain response, plus the desired features (e.g., frequency lowering, 
noise reduction, WDRC release time). Real-ear aided response will be measured with a probe 
microphone system and frequency-gain response adjusted to meet prescribed NAL-NL targets.  Each 

HA outcomes in Older Adults: 
participant will be tested at the hearing aid fitting and again and 6 weeks post-fitting.  During that time 
they will wear the hearing aids in their own environment.  
 
 
Outcomes. Two important goals in hearing-aid processing are to improve speech intelligibility and 
quality.  
 
Speech intelligibility.  Speech intelligibility will be tested using low-context (IEEE51) sentences in quiet 
and in babble at a range of signal-to-noise ratios (SNRs). The processing will be provided by the settings 
of the wearable hearing aids; and the patient will be aided binaurally.  Subjects will be tested in a 
double-walled sound booth with the test signal (conversational speech level) presented through a 
speaker.  The speaker will be positioned at a typical conversational distance (approximately 1m) and 
azimuth (0◦) and the subject will respond by repeating the sentence heard.  The hearing aid will be 
programmed by the research audiologist.  Both the research assistant (who will conduct the speech tests) 
and the patient will be blind to the processing condition.  Based on our previous data and on desire to 
sample realistic listening conditions we expect to use SNRs ranging from 0 to +10 dB.  Our protocol for 
measuring speech intelligibility is as follows.  The listener is seated in a double-walled sound booth and 
speech is presented to the listener at conversational levels in free field.  Speaker distance (~ 1 m) and 
azimuth (0◦) mimic a conversational situation.  A locally-developed Matlab interface allows the listener 
to signal for presentation of the next sentence and for scoring of correct repetition of key words by an 
experimenter seated outside the sound booth.  To confirm reliable scoring, an audio file of the listener’s 
response is digitally stored and rescored by a second tester who is blinded to the initial scoring.  
 
Speech quality.  There are many situations where speech intelligibility is high but sound quality is still 
rated as lacking. In addition, sound quality is a critical component to successful hearing aid outcomes.  
Quality ratings will therefore be obtained in addition to the intelligibility tests. Perceptual quality ratings 
will be obtained using a rating scale ranging from 1 (poor sound quality) to 10 (excellent sound 
quality).   The rating scale will be implemented with a slider bar that registers responses in 0.05 
increments. Listeners will make their selections from the slider bar displayed on the computer screen by 
using a customized interface that included a point-and-click method for recording and verifying rating 
scores.  The timing of presentation will be controlled by the subject.  This rating scale has been used 
successfully in quantifying the differential effects of hearing aid signal processing algorithms on sound 
quality ratings by both normal-hearing and hearing-impaired listeners. 
 
 
Handicap reduction (subjective outcome). Objective measures provide insight into treatment efficacy, 
but effectiveness depends on the psychosocial adjustments to hearing loss that cannot be measured in a 
sound booth. Therefore self-administered scales are a critical component of assessing treatment 
effectiveness.  
 
Three subjective measures will be used: 
 
Effectiveness of Aural Rehabilitation (EAR).  The EAR measures intrinsic issues of hearing loss 
(functional, physical, emotional, and social impairment), as well as extrinsic factors such as the comfort, 
convenience, and cosmetic appearance associated with hearing devices. Two modules, the “Inner EAR” 
(intrinsic) and the “Outer EAR” (extrinsic), were created.  Both scales are brief (10 domain items, in 

HA outcomes in Older Adults: 
addition to one or two global questions). The EAR scales were developed and validated by the PI and 
colleagues. Item reduction was based on inter-item correlation, internal consistency, and factor analysis. 
Final scales take an average of 5 minutes to complete, have well-distributed responses, and no ceiling or 
floor effects. The effect size of the Inner EAR is high (2.1). The Minimal Clinically Important 
Differences (MCID) of the EAR is 6.0 points (on a 0 to 100 scale).  
 
Adherence. We will evaluate adherence using 2 questions: “Do you use your hearing aids?” and “How 
many hours a day do you use your hearing aid?” In our previous work, we used these questions and 
found responses to be well-distributed.  While responses correlate with the Inner EAR (r=.35, p<.001) 
and satisfaction with amplification (r=0.4I, p<.001), the moderate correlation coefficients suggest that 
adherence is an important construct that reflects more than mere function and satisfaction. 
 
Speech and Spatial Qualities of Hearing (SSQ) questionnaire.  The SSQ addresses static and dynamic 
listening environments, and includes situations with several types of background noise and where the 
target talker is unpredictable.  The SSQ items are categorized as: understanding speech; judging sound 
location/distance; and sound clarity/naturalness.  Patients rate how well they performed in the specified 
situation.  The SSQ is included because we are interested in difficult listening situations which require 
cognitive resources, such as those involving background noise and multiple talkers.  In a recent study23 
we collected SSQ data along with a variety of other objective measures, including ability to hear speech 
in complex noise.  In those data, older listeners’ reports of listening in complex situations was much 
more variable than for younger listeners with comparable hearing thresholds.  
 
Hearing aid use verification: Approximately one week after Fitting A, and one week after Fitting B 
participants will return to the lab to take the Practical Hearing Aid Skill Test (PHAST). This test 
requires participants to demonstrate hearing aid use tasks (e.g insertion/removal of hearing aid, changing 
batteries, and cleaning). This test insures participants are using and wearing their hearing aids 
appropriately.  
 
Mid-fitting follow-up: Three weeks after hearing aid fitting participants will be contacted via telephone 
or email. The purpose of this follow-up is to insure participants are wearing their aids, and to assess any 
problems participants are having with the hearing aids. 
 
Datalogging: During the one week post fitting verification and 6 weeks post fitting visit hearing aid data 
logs will be measured. This hearing aid feature allows the PI to identify how many hours the hearing aid 
has been in use.  
 
 
Data Management 
Each subject will receive a study code and that code will be used for all study data. The link 
between the subject name and code are password-protected and stored on a HIPAA-approved 
server with server security managed by Northwestern School of Communication computer 
support staff. All research staff will be trained in appropriate Human Subjects protection 
procedures, including confidentiality. Data is accessible only to study staff via password-
protected files. Additionally subject data may be shared with collaborators at the University of 
Colorado Boulder. When sharing information will be exchanged via secure FTP. All (de-
identified) data will be stored in a secure database accessible via password by study staff at either 

HA outcomes in Older Adults: 
site. Weekly meetings across sites will include discussion of subject confidentiality. All 
personnel involved at either site will complete appropriate Human Subjects Protection training. 
Any unanticipated problems will be reviewed by the PI and reported as required. 
Withdrawal of Subjects 
Subjects are free to discontinue testing at any time at any point of the study, for any reason. All testing 
will be done in a manner to ensure safety of our subjects (e.g presenting sounds at a comfortable 
listening level) If a subject decides to withdraw from the research study only the data collected up to that 
point will be used with their permission. If they do not provide their permission their data will be 
withdrawn completely. A participant may be removed from the study if they lose or damage the study 
aids, do not wear the study aids for more than 6 hours a day, or are unable to adhere to the prescribed 
study schedule and tasks. In the event that a participant is removed from the study without their consent 
compensation will be pro-rated based upon the duration the participant remained compliant with study 
tasks and procedures. Once a participant is unable to continue with the study, compensation will end.  
 
Statistical analysis plan 
Outcome measures between the optimal and suboptimal conditions will be compared using a paired t-
test.  We expect customized processing settings, which will utilize our cognitive and peripheral test 
batteries, will result in statistically significant and clinically meaningful improvements when compared 
to traditional fittings.  We will identify any acclimatization effects by monitoring changes in outcomes 
observed over time.  All subjects are expected to fully acclimatize to the hearing aid device by the end of 
the six-week trial.   We will use a paired t-test analysis to compare the outcomes between the “high 
modification” and “low modification” conditions.  This experiment will be powered to detect mean 
differences of 0.5 standard deviations with a sample size of 45 at 90% power and alpha=0.05.   
 
Sharing of Results with Subjects 
Results of standard clinical procedures (e.g auditory testing) will be made available to 
participants at their request. Participants often have questions about their hearing and hearing 
aids. Counseling and recommendations will be done by or under the supervision of Dr. Pamela 
Souza the study PI and clinical audiologist. If research participants request the results from the 
research testing or cognitive testing, these results will be provided to the participant with the 
explanation that they are for “research purposes only” and not meant as a diagnostic tool or 
clinically reliable.  
Recruitment Methods 
Individuals in our lab subject pool who have expressed an interest in future studies will be 
contacted by phone or email (whichever they have indicated as a preferred contact) by the PI or 
her research assistant. Additional subjects will be recruited as needed by: (a) Flyers posted in our 
clinic and on community bulletin boards (b) Letter to potential participants. These letters will be 
sent to potential participants in the Aging Research Registry and the Northwestern University 
Audiology Clinic (c) newspaper advertisements 
Subjects will receive $10 per hour for participation. Participants will receive a bonus payment of 
$40 after 6 weeks of wearing Fitting A, and $50 after 6 weeks of wearing Fitting B. Therefore in 
experiment 2, a subject will be paid $250 if they complete all study visits/tasks. (8 study visits 
lasting 2 hours paid at $10/hour: $160 + bonus payments of $40 and $50 = $250 total)The 

HA outcomes in Older Adults: 
subject is paid by check or cash. Typically this is done at the end of each study visit (for multiple 
visits), but some subjects opt to receive a single payment at completion of the entire study. We 
follow the subject's preference in this matter. The subject will be asked to sign a receipt verifying 
that they have received payment. A subject who withdraws from the study retains the amount 
paid for the portions of the study that were completed, but forfeits pay for the uncompleted 
portions of the study. Potential subjects will not be paid for the hearing test which is done to 
determine whether criteria for participation has been met.  
Provisions to Protect the Privacy Interests of Subjects 
During the consent process a lab member will explain that their identifiable information will not 
be used. Each participant will receive a study code that will be used for all study data. The only 
link between identifiable data and a study code will be on a password protected HIPAA-
approved server with server security managed by Northwestern School of Communication 
computer staff.   Before starting a study procedure the lab member will explain the task and 
reiterate that they are free to stop at any point. During the administration of questionnaires or 
cognitive testing the tester will remind the subject they can decline to answer any question they 
feel uncomfortable answering without any negative consequences.  
Consent Process 
Prior to enrollment potential participants will have a hearing and cognitive test with 
authorization by a screening audiogram consent form. These tests will allow us to exclude 
potential participants from enrolling in the study who are ineligible based upon their hearing 
status or over-enrolling participants in a particular working memory group. If participant is 
eligible based upon their screening results, they will be enrolled in the study with separate 
consent. All subjects will provide their consent to study procedures to the investigator or her 
research assistants. This process will take place in the Hearing Aid Laboratory, prior to any 
research procedure taking place. All consent forms are stored in a locked file cabinet drawer 
within the Hearing Aid lab (a locked laboratory). An unlimited amount of time will be provided 
to the participant to ensure they have adequately reviewed the consent form and all questions 
have been addressed by study staff. Following the subject’s opportunity to read the consent 
document, study staff will review each section with participant to clarify the study or any 
procedure, and ensure understanding. Additionally consent forms may be provided to a potential 
research participant before a study visit is scheduled so they may take extra time to review before 
committing to participation. All participants will receive a copy of their signed consent form.  
Non-English Speaking Subjects 
At this time we are unable to include non-English speaking subjects, because the study requires 
repetition of English-language materials.