Investigating the Relationship Between Directional Microphones, Compression, and Working Memory in Realistic Spatial Conditions.
Phase: NA
Conditions: Hearing Loss, Sensorineural
Sponsor: Northwestern University

 
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STUDY TITLE: 
 
Hearing Aid Processing and Working Memory in Realistic Spatial Conditions 
 
NCT Number: 
 
NCT04521166 
 
 
DOCUMENT DATE:  
 
6.25.2024 
 
Final Protocol Approval by IRB #STU00210459:  
 
4.12.2023 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

 
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STUDY TITLE: 
Investigating the relationship between directional microphones, compression, and 
working memory in realistic spatial conditions.  
 
PRINCIPAL INVESTIGATOR: 
Name: Pamela Souza 
Department: Communication Sciences & Disorders 
 
CO-INVESTIGATOR: 
Name: Varsha Rallapalli 
Department: Communication Sciences & Disorders 
 
STUDENT INVESTIGATOR (complete this section only if the project 
is student-initiated): N/A 
 
 
VERSION DATE: 
3.29.2023 
 
Check any applicable boxes in the table below – you will be asked for 
further detail on these topics later in the protocol form: 
 
Indicate Vulnerable 
Population(s) to be Enrolled 
☐ Children  
☐ Cognitively Impaired Adults   
☐ Pregnant Women (IF the research activities will affect   
the pregnancy or the fetus) 
☐ Prisoners (or other detained/paroled individuals)  
 
International Research 
(check this box if you will 
collect data from 
individuals located outside 
the United States) 
 
 
☐ 
Research involving external 
collaborators (some 
research activities will be 
carried out by individuals 
not employed by 
Northwestern or NU 
affiliates) 
 
 
 
☐ 
 
Research has U.S. Federal 
government funding (e.g., 
NIH, NSF, other federal 
agencies/departments) 
 
☒  
 
 

 
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1.0 
Purpose of the study: 
The purpose of this research is to understand how patient variables interact with 
hearing aid signal processing in realistic listening conditions in order to 
effectively treat hearing-impaired individuals in communications situations that 
are most important to them. 
 
2.0 
Background / Literature Review / Rationale for the study: 
Hearing loss is prevalent in approximately 37 million adults over the age of 18 
years in the United States [1]. Hearing aids are the typical rehabilitative approach 
for most individuals with permanent hearing loss. While there is evidence that 
hearing aid use significantly improves the quality of life [2-4], hearing aid 
adoption rates are as low as 30% [4,5], due to lack of perceived benefit in difficult 
listening environments [3]. If hearing loss is not treated adequately, it can lead to 
broader consequences including social isolation and depression [6,7]. Therefore, 
an individualized approach to hearing healthcare including selection of hearing 
aids and customization of settings to the listener’s abilities and environment, is 
integral to adherence to treatment, social engagement, and listener satisfaction [8]. 
The central focus of this research proposal is to inform the choice of hearing aid 
settings based on individual variability. 
 
Signal modifications caused by collective hearing aid processing and 
environmental conditions affect individual benefit from hearing aids.  An 
important relationship that has heavily influenced audiology practice is the 
finding that listeners with lower working memory capacity are disadvantaged by 
hearing aid signal processing that substantially modifies the speech signal (such 
as fast-acting wide dynamic range compression, or WDRC [9,10]). In response to 
this finding, researchers and some hearing aid manufacturers have advocated for 
less aggressive signal modification (such as slow-acting WDRC, which gradually 
adjusts hearing aid gain) and others have suggested that measurement of working 
memory or other cognitive abilities should be part of the clinical hearing aid 
fitting process.   
 
Importantly, the relationship between working memory and WDRC is strongest 
under adverse listening conditions (e.g., high levels of background noise [9-12]) 
and diminished in ideal listening conditions (e.g., speech in quiet [9-12]). 
However, there is a critical limitation of the research that has supported this 
conclusion. All previous studies on this topic assumed the use of omnidirectional 
microphones in unrealistic spatial conditions, such as co-located speech and noise.  
Such conditions fail to recognize that most hearing aids are fit with directional 
processing that may improve the listening environment [13, 20], and that typical 
environments contain speech and noise signals in a range of spatial locations. 
Further complicating this issue, directional microphones vary in the amount of 
benefit across listening conditions [13]. Therefore, the proposed research aims to 
understand how the relationship between working memory and WDRC changes in 
the presence of microphone directionality in different listening conditions. 
 

 
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The aims of this study are: 1) to examine the relationship between working 
memory and hearing aid signal processing (WDRC in the presence of microphone 
directionality) in spatial conditions ideal for directionality, 2) to examine the 
relationship between working memory and hearing aid signal processing (WDRC 
in the presence of microphone directionality) in realistic spatial conditions.  
 
The proposed research will help answer whether working memory remains an 
important variable to measure when microphone directionality and WDRC 
features are used in combination, thus providing evidence for whether working 
memory should be added to the standard hearing aid fitting protocols. 
 
3.0 
Inclusion and Exclusion Criteria: 
Inclusion criteria: 
- 
18 years or older  
- 
Sensorineural hearing loss with pure-tone thresholds between 25-70 dB HL at 
octave frequencies between 500 and 3000 Hz 
- 
Speak English as their primary language 
- 
Normal or corrected-to-normal vision (<=20/50) 
- 
Participants will be in good health (self-report)  
 
Exclusion criteria: 
- 
Clinically significant unstable or progressive medical conditions 
- 
Participants who score <23 on the cognitive screening test (Montreal 
Cognitive Assessment) 
- 
Evidence of conductive hearing loss or middle ear issues 
- 
Significant history of otologic or neurologic disorders 
- 
Evidence of significant asymmetry between ears 
- 
Non English-speaking or non-native English speaking 
 
We may enroll a small group (n=30) of listeners with normal hearing, defined as 
pure-tone thresholds of 25 dB HL or less at octave frequencies between 250 and 
3000 Hz. This group may be enrolled for the purposes of test validation, or to 
study the effects of hearing loss on the outcome measures. With the exception of 
having normal hearing, those participants will follow the inclusion and exclusion 
criteria described above.  
 
The study will not recruit special populations such as adults unable to 
consent/cognitively impaired, minors, prisoners, or other detained individuals.  
 
4.0 
Sample Size: 
The study will recruit 120 participants over a 3-year period. Each experiment will 
recruit approximately 30 participants (additional 10 account for pilot testing and 
attrition) for a total of 3 experiments.  
 
Sample size considerations were based on the primary analyses of a mixed effect 
model with fixed effects for WDRC, working memory, and the interaction. 

 
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Simulations were performed based on a range of effect sizes and estimates of 
between subject and within subject variances. Our sample size of 15 subjects per 
working memory (high vs low), will provide at least 80% power to detect 
reasonable effect sizes for all three effects. Specifically, we assumed a 
conservative subject variance estimate of 0.01 and a residual variance estimate of 
0.01 from pilot data, marginal effects for working memory of 0.70 (high) and 0.53 
(low), and marginal effects for WDRC of 0.75 (fast) and 0.48 (slow). In 
simulations assuming a two-sided type one error, we had adequate power to detect 
all three effects. In simulations assuming less conservative variance estimates, our 
sample size will provide adequate power to detect even smaller effect sizes. 
Specifically, we assumed a subject variance estimate of 0.008 and a residual 
variance estimate of 0.006, marginal effects for working memory of 0.38 (high) 
and 0.17 (low), and marginal effects for WDRC of 0.33 (fast) and 0.22 (slow). 
We anticipate a range of effect sizes and variance estimates for models within 
each level of directionality, and thus considered simulations from a range of 
assumptions.   
 
5.0 
Recruitment and Screening Methods: 
Recruitment process: 
The proposed study will recruit 120 adults (18 years or older) over a three year 
period. Participants will be primarily recruited from an existing database in the 
lab that has over 300 adults with hearing loss who are interested in study 
participation and agreed to be contacted for future research. The lab also has 
access to a Communication Research Registry, a confidential database for 
individuals interested in continuing research participation within the Northwestern 
School of Communication. Additional recruitment will take place through the 
department’s audiology clinic, local senior centers, and local Hearing Loss 
Association of America (HLAA) chapter using flyers. Recruitment flyers will also 
be disseminated through flyers on bulletin boards throughout the Northwestern 
campus. Advertisements will be posted in local boards.Interested participants will 
be contacted by the research staff via phone or email as preferred by the potential 
participant. At this time, the participant will be provided basic information 
regarding study procedures and inclusion criteria.  
 
Screening process: 
Prior to enrollment in the study, potential participants will go through a screening 
process. The screening procedure will take approximately 60-80 minutes. The 
following tests may be conducted to verify eligibility for research inclusion: 
 
Test 
Description/Purpose 
Exclusion Criteria 
Case history 
Written administration; questions 
re: onset/nature of hearing loss, 
hearing aid use, otologic and 
medical history; CEDRA 
questionnaire [21] 
Significant history of otologic/neurologic 
disorders 
Otoscopy 
Visual examination of pinna, ear 
canal, and ear drum 
Significant impaction of wax, active 
discharge; exclusion will be determined in 

 
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conjunction with tympanometry when 
appropriate 
Tympanometry 
Test to determine middle ear status 
B-type tympanogram suggesting unhealthy 
middle ear status 
Audiogram* 
Air conduction (250 Hz to 8000 
Hz) and bone conduction (500 Hz 
to 4000 Hz) testing to determine 
degree and type of hearing loss 
Evidence of conductive hearing loss (air-
bone gap > 10 dB HL); Hearing loss > 70 
dB HL at any frequency between 250-3000 
Hz;  
Evidence of significant asymmetry between 
ears (≥ 15 dB HL at 3 or more frequencies 
OR ≥ 20 dB HL at any 2 frequencies) [14] 
Monosyllabic 
word recognition 
Percentage of phonetically-
balanced words repeated in quiet 
at a comfortable loudness.  
Evidence of significant asymmetry between 
ears [15] 
Montreal 
Cognitive 
Assessment 
(MoCA) [16] 
Cognitive screening test that 
assesses orientation to time and 
place, short-term memory, and 
ability to follow simple commands 
The scope of this study does not include 
cognitive impairments, therefore, we will 
exclude participants with a score lower than 
23 [17] (suggests dementia) 
Vision Screening 
Screen for normal or corrected-to-
normal vision using a 
letter/number chart 
Normal/corrected-to-normal vision is 
required because the study involves 
selection of response options seen on a 
computer screen. MoCA (above) involves 
identifying/copying visual objects. We will 
exclude subjects who fail vision screening. 
 
All participants must be native speakers of English because our outcome measure 
is speech intelligibility of English sentences [18] from a local talker database. 
Therefore, proficiency in English (based on self-report) is required for the validity 
of the results. The participants should also be in general good health (based on 
self-report). 
 
*During the COVID-19 pandemic, it may not be possible to obtain new 
audiograms in the lab due to risk of exposure to both the participant and the 
research staff. For participants recruited from outside our lab pool or any 
participant who does not have a valid audiogram, we may adopt the following 
procedures:  
a) Request the participant to provide a copy of their existing audiogram (if 
available) completed by an audiologist outside of our lab. The participant will 
be asked to upload a copy of their hearing test via REDCap. If a participant is 
unable to access REDCap, they can send a copy of their hearing test via fax or 
to an encrypted email address.    
b) We may obtain air conduction thresholds using a validated remote automated 
test (e.g., GSI AMTAS Flex [22]) delivered to the participant via a tablet and 
calibrated headphones. The participant will be asked to complete the test in a 
quiet room with minimum distractions. The automated hearing test is HIPAA-
compliant and FDA-registered. 
 
Additional explanation: 

 
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Our study population is adults with hearing loss. Therefore, we will include 
individuals with sensorineural hearing loss with pure-tone thresholds between 25-
70 dB HL at octave frequencies between 500 and 3000 Hz. This meets the criteria 
for a mild to moderately-severe hearing loss. This is the typical range of hearing 
loss for which individuals seek hearing aids and also the range for which hearing 
aids can provide sufficient gain. Participants should have no significant history of 
otologic or neurologic disorders as these disorders are beyond the scope of the 
study. The participant must have normal or corrected-to-normal vision because 
the cognitive tests involve visual (reading) tasks. Exclusion criteria include 
conductive hearing loss and middle ear issues (e.g., active discharge, significant 
wax impaction) as these conditions may preclude the use of a hearing aid and are 
outside the scope of the study. Exclusion criteria also includes asymmetry 
between ears [16]. Asymmetry between ears may require different hearing aid 
settings for each ear which may confound the results. Participants who do not pass 
the cognitive screening test (< 23 on the Montreal Cognitive Assessment [16, 17]) 
will also be excluded because cognitive impairments are beyond the scope of this 
study. 
 
6.0 
Research Locations: 
The proposed work will be conducted within the Hearing Aid Lab (PI: Dr. Pamela 
Souza) and in a virtual sound room (ViSoR) at Northwestern University. The lab 
is a 600 square foot space that includes an 8’ x 8’ double-walled IAC sound 
booth. The lab also has a meeting area with a large desk and chairs for case 
history-taking, cognitive assessments, and counseling, a participant waiting area 
with educational materials on hearing loss resources and support, and a secure file 
storage area. The research may also be conducted in a separate 10’ X 7’ sound-
treated space (Frances-Searle room 1-387) that has been recently added as part of 
the Hearing Aid Lab. 
 
The virtual sound room (ViSoR) is within the Northwestern University Center for 
Audiology, Speech, Language and Learning (NUCASLL) in a building adjacent 
to the Hearing Aid Lab. The research staff involved in this study have access to 
this room.  
 
Due to the COVID-19 pandemic, participant research visits may be conducted 
remotely using Northwestern IT-approved (and HIPAA-approved) video 
conferencing or phone. The research staff will conduct these visits from a private 
room in their apartment and no one else will be present during the research study. 
The research staff may also conduct these virtual visits from the hearing aid lab or 
an office space. Participants will perform the remote testing from their respective 
places of residence/a quiet place of their convenience. The virtual visits will be 
conducted either through Zoom or Microsoft Teams or WebEx applications. The 
platform used will be determined by participant preference. 
 
7.0 
Multi-site Research (research that involves external collaborating 
institutions and individuals): N/A 

 
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8.0 
International Research (where data collection will occur outside 
the United States and U.S. territories): N/A 
 
9.0 
Procedures Involved: 
 
The proposed research will measure speech intelligibility and signal fidelity with 
a combination of hearing aid settings under a variety of spatial conditions (Aim 1: 
ideal; Aim 2: realistic) for hearing-impaired listeners with different working 
memory capacities. The proposed research is a clinical trial and will use 
laboratory hearing aids to provide various combinations of hearing aid signal 
processing. Using a mixed design, individual variability in auditory and working 
memory capacity will be related to speech intelligibility and signal fidelity across 
test conditions. Test procedures including stimuli and outcome measures 
described below are common to both Aims 1 and 2.  
 
Study tasks for all experiments will include the following steps per subject: 
 
Session 1 
Approx. 
Duration 
(2 hours) 
Session 2 
Approx. 
Duration 
(2 hours) 
Session 3 
Approx. 
Duration 
(2 hours) 
Candidacy 
assessment 
60-80 mins 
Earmold + 
Hearing Aid 
Fitting 
45-60 mins 
Outcome 
measurement  
(Speech 
intelligibility 
testing, 
localization) 
continued 
60-120 mins 
Cognitive 
test* 
15-30 mins 
Outcome 
measurement 
(Speech 
intelligibility 
testing) 
60 mins 
 
 
Earmold 
impression 
15-20 mins 
 
 
 
 
*May include tests of working memory, executive function, and processing speed 
 
Session 2 will take place ~10-15 days after session 1 to allow for time taken for 
the custom earmold order to be received. There is no minimum gap required 
between sessions 2 and 3. Session 3 may not be required for all experiments or 
participants.  
 
Stimuli: 
Recorded speech materials (words, sentences, or passages) will be presented. 
These speech materials will be combined with multi-talker babble at varying 
levels (including no noise), and the intensity of the stimuli will be adjusted to 
represent typical conversational speech (65 dB SPL).  

 
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The listener will be fit with hearing aids that are either commercially available or 
an open-platform hearing aid or a computer simulation of a hearing aid [e.g., 9] 
that allows flexible adjustments compared to commercial hearing aids and ensures 
adequate scientific rigor. The hearing aids will be fit to a foam/ear tip or a custom 
earmold and the amplification levels will be set appropriate to the individual’s 
hearing. If a computer simulation is used, the amplified/processed sounds will be 
presented via headphones or earphones and the amplification levels will be set 
appropriate to the individual’s hearing.  
 
Earmold impression: First, the ear is visually inspected with an otoscope (lighted 
magnifying scope). Then a cotton/foam block and soft impression material are 
placed in the ear. The material is left to set for about 3 mins after which it is 
removed along with the cotton/foam block and is used to order an earmold for 
later testing. This is a standard clinical procedure.  
 
Loudness discomfort levels: Participants will be played sounds at progressively 
louder levels and asked to verbally indicate the maximum point of listening 
comfort. Loudness discomfort levels will be measured at 0.5 and 3 kHz and used 
in combination with patient report. This is a standard clinical test used to verify 
that stimuli levels are not uncomfortably loud. 
 
Hearing aid fitting: The ear is visually inspected using an otoscope. A small soft 
plastic tube is inserted into the ear canal and is used to measure the sound output 
of the hearing aid. The hearing aid + earmold are placed in the ear. The 
participant is seated in front of a speaker and sound is played from it. The sounds 
may be speech or noise with similar frequency content to speech, at levels ranging 
from soft to conversational to loud speech (50-80 dB SPL). In order to verify that 
the hearing aid is not uncomfortably loud, a stream of loud beeps (85-90 dB SPL) 
are played for 2-3 secs. Alternatively, the hearing aid fitting may be completed in 
a test box with a standard coupler instead of the participant’s ears. These are 
standard clinical procedures used to adjust the hearing aid so that the 
programming settings are appropriate for the participant’s hearing loss. Recently, 
hearing aid manufacturers have included the capability to fit hearing aids 
remotely. If needed, hearing aids may also be fit remotely using hearing aid 
manufacturer-specific software. 
 
Outcome measures: 
Speech recognition: The recorded speech materials that have been electronically 
processed and mixed with multi-talker babble, will be presented through 
earphones or speakers. The speech material and noise may be presented through 
single or multiple speakers and from different locations in the test room. The 
participant will listen through the hearing aids for the duration of the experiment. 
The participant’s task would be to either repeat the speech or select it from a list 
of choices on a computer monitor or provide a written response.  
 

 
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To minimize contact with the participant during the COVID-19 pandemic, the 
participant may be provided with a tablet or computer monitor to control (using a 
touchscreen, keyboard or mouse) the presentation of the stimuli via a graphical 
user interface. The participant will be recorded repeated the speech so that their 
responses may be scored later by the experimenter (also see section 17). The 
participant will be guided with on screen instructions and may reach the 
experimenter via an intercom at any time.  
 
Localization: Listeners may be asked to indicate where they perceive a sound to 
have originated. The sounds may be presented through speakers or headphones. 
Responses may be given verbally or via an interface using a touch screen or 
keyboard and mouse. Since hearing aid processing (e.g., directional microphones) 
is known to affect localization of sounds [23], this measure may provide 
additional insights into hearing aid outcomes. 
 
Working memory task: The Reading Span test (RST [19]) will be used to measure 
working memory for each participant. The participants are instructed to read a set 
of sentences presented on a computer screen, one at a time, and make a judgment 
about the meaningfulness of each sentence. After a set of 3-6 sentences they are 
asked to recall either the first or last words of all the sentences. Scores are based 
on the number of words correctly recalled in each set.  
 
Audio Visual Divided Attention Task (AVDAT; [25]): The AVDAT is comprised 
of three span tasks: auditory, visual, and dual (auditory and visual). Participants 
are presented with either letters or numbers, depending on the test, and their task 
is to correctly recreate the given sequence. The test progresses by adding one 
number or letter to the previous span and ends after three consecutive incorrect 
responses have been submitted, thereby pinpointing a participant's working 
memory span. 
 
Executive function: This is the strategic control of mental processes and 
determines how cognitive resources are allocated to various tasks.  
 
The Stroop Test. This is a measure that assesses reaction time and conscious 
versus automatic visual processing. This test takes approximately 5 minutes to 
administer. Participants are instructed to read black text that indicate the names of 
colors, as quickly as possible. The second part of the assessment includes 
participants seeing colored lines, and they are instructed to name the colors on the 
page as quickly as they can. The third part of administration is the participant will 
then be given a list of color names, where they say the color of each word, not 
read the text itself. For example, if the word “yellow” was written in green ink, 
the correct response is “green”. Participants are timed for each of the three 
segments.  
 
The Flanker Test: We will administer two tasks tapping this interference control 
ability and compute a z-score aggregate to obtain a stable estimate. In the arrow 

 
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flanker task, participants see a > or < sign, surrounded by two > or < signs on 
either side (e.g., >>>>>, <<><<). Their task is to focus on the middle sign and 
decide whether that sign is pointing to the left or the right as quickly and as 
accurately as possible by pressing one of the two buttons (left or right). The 
reaction time difference between the compatible (e.g., >>>>>) and incompatible 
stimuli (e.g., <<><<) will be used to index interference control ability. In the 
letter flanker task, participants will see either a letter G or H in the middle, 
surrounded by two Gs or Hs on either side (e.g., HHHHH, GGHGG). 
Participants’ task is to focus on the middle letter and determine as quickly and as 
accurately as possible whether it is a G or an H. Again, the reaction time 
difference between the compatible (e.g., HHHHH) and incompatible (GGHGG) 
stimuli will be used as the index of interference control ability.  
 
Processing speed: This is the rate at which information is treated in the cognitive 
system. Individuals with higher processing speed are expected to have better 
outcomes especially when the conditions are more challenging.  
 
WAIS-III Coding/Symbol Search [24] (3 minutes): Participants are presented 
with a series of letters and a key at the top of the page with a corresponding 
number. Below each letter is a space to write the corresponding number, and 
participants are asked to fill in as many of the numbers as they can within a 
certain amount of time.  
 
 
Rationale for including additional cognitive measures: The above-described 
measures including AVDAT, measures of executive function, and processing 
speed may be included to explain variability in outcomes that may not be captured 
by the reading span test.  
 
Peripheral auditory abilities: Participants may be asked to listen to tones, sounds 
of different frequencies and modulation, or noises of different lengths to 
determine auditory abilities beyond simple hearing thresholds. These measures 
are quick, non-invasive, and are presented at safe listening levels (i.e., 65-75 dB 
SPL) and pose little to no physical risk to participants. These sounds will be 
presented over headphones or speakers in a sound-treated room and may take 30 
minutes to complete.  
 
Acoustic measurements: After the completion of experiment by the participant, 
de-identified hearing aid fitting data may be retrieved from NOAH, the hearing 
aid programming software for additional analysis. This hearing aid fitting data 
may be programmed back onto the hearing aid in order to record output on an 
acoustic manikin within the same test conditions as the behavioral experiment. 
The recorded output will be used to measure signal fidelity across conditions and 
relate acoustic measurements with speech intelligibility and individual patient 
characteristics such as age, degree of hearing loss, and cognitive abilities. This 
part of the experiment does not directly involve the participant and will only be 
conducted with de-identified materials.  

 
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Additional procedures for remote data collection: If the participant is provided a 
tablet and calibrated headphones for automated audiometry, the following 
procedures will be used. The participant will be provided with detailed 
instructions on the phone or through a HIPAA-compliant video conferencing 
platform. The participant will be requested to complete the testing in a quiet 
location, with minimum distractions. In order to monitor the surrounding noise 
levels during the testing, the participant may be asked to record the noise levels in 
their room using a publicly available sound level meter application (e.g., Decibel 
X, NIOSH SLM). Obtaining a record of the noise level during the testing is 
important as high background noise may obscure the results of an audiogram. 
 
No identifiable information will be placed on the tablet at any stage of the 
experiment. Completed data from each participant will be retrieved from the 
tablet (and erased) and housed on a secure server, before providing the tablet to 
the next participant.  
 
The remote testing equipment (tablet(s) and calibrated headphones) will be 
provided to the participant using one of the following methods (depending on 
convenience):  
a) The participant may pick up the equipment from a research staff member 
from the curbside/parking lot by the Frances-Searle building. The 
participant may also return the equipment to the research staff member at 
the same location, upon completion of the experiment.  
b) The equipment may be delivered to and picked up from the participant’s 
residence by a research staff member. 
c) The equipment may be mailed to the participant with a return box and 
shipping label.  
 
Communication regarding the details of pickup and return of the equipment 
(including preferred method and date/time/location) will take place over the 
phone or via email. A record of the agreed upon details will be maintained by the 
research staff. The participant will be sent a reminder 24 hours before the 
scheduled time, either via email or phone (depending on the participant’s 
preferred method of contact). A tracking number will be associated with any 
shipments and the package will be insured. In the event that the participant does 
not return the equipment by the agreed upon time/date, we will follow up with 
reminder emails or phone calls to determine the cause for delay and to provide 
them with alternative options for returning the equipment within a reasonable 
time frame. Participants will not be charged and financial compensation will not 
be withheld in the event of loss or damage to any equipment.  
 
We will adhere to strict infection control procedures by thoroughly cleaning all 
surfaces of the tablet and headphones before and after a participant has used them. 
In addition, we will maintain 2-3 sets of equipment to reduce the number of users 
of the same equipment.  

 
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10.0 Research with Vulnerable Populations: N/A 
 
11.0 Incomplete Disclosure or Deception: N/A 
 
12.0 Consent Process:  
Prior to enrollment in the study, potential participants will have a hearing, vision, 
and cognitive test with authorization by a screening consent form. These tests will 
allow us to exclude potential participants who are ineligible based on their 
hearing, vision, or cognitive status from enrolling in the study. These tests will be 
built into the first visit tasks and will last 60-80 minutes. If the participant is 
eligible based on the screening process, he/she will be consented for the 
experimental procedures using a separate form. If a participant is not eligible 
based on screening, they will have the option to authorize future contact and 
authorize the lab to retain the screening audiogram and cognitive test results. 
Consenting will take place in the Hearing Aid Lab, prior to any research 
procedure taking place. All consent forms are stored in a locked file cabinet 
within the Hearing Aid lab (locked lab). The potential participant will be provided 
unlimited amount of time to review the consent forms and ask any clarifying 
questions. Following the participant’s opportunity to review the consent form, the 
researcher will review each section with the participant to clarify any study 
procedure and ensure understanding. All participants will be offered a copy of 
their signed consent form with the option to decline. The researcher will 
document the consent process and the participants’ receipt of/decline of a signed 
copy on a study flow sheet. Both participant and staff will initial the flow sheet to 
verify that the consent form was provided or that a copy was declined.   
Please note that during the consent process, the researcher will explain to the 
participant that their identifiable information will be kept confidential and will not 
be used.  
 
Due to the COVID-19 pandemic, virtual consent will be obtained from any newly 
enrolled study participants in order to minimize risk of exposure. Participants will 
be consented using one of two procedures, determined by participant preference: 
 
Option 1: The participant will be consented electronically using REDCap. The 
participant will be required to “sign” by typing their name and enter the date. The 
participant will be able to review the consent form as many times as they need to, 
go back and forth through sections, and take their time before providing their 
consent. They may save their progress on the form and return to it at a later time if 
needed. The participant may contact a study team member as needed to provide 
any clarifications regarding any part of the consent form via phone or email or 
video before the deciding to provide their consent. All information required for 
informed consent will be available on the eConsent forms. Consent forms for this 
study do not have any associated external material or hyperlinks. In order to 
ensure the identity of the signer, the REDCap consent form can only be accessed 
by the email address that it is sent to (i.e., the email address provided by the 

 
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participant). In addition, the participant will be provided with a predetermined 
passcode via phone or video. At the time of accessing the electronic consent form, 
the participant must enter the passcode which will be internally compared with the 
stored version entered by the study team member. The participant will be granted 
entry only if the passcode matches. The participant will have the option of saving 
a copy of their signed eConsent forms as PDFs. A study team member will review 
the submitted eConsent form and electronically sign and date as confirmation.  
 
Option 2: The participant will be sent a consent form via encrypted email, which 
they will sign and date, scan/take a photo of, and email back to the research staff. 
The participant may contact a study member as needed to provide any 
clarifications regarding any part of the consent form via phone or email or video 
before the deciding to provide their consent. The staff member will review the 
submitted consent form and sign and date as confirmation. The participant will be 
sent a scanned copy of the signed consent form for their records.  
 
 
13.0 Research with Children – Parental Permission, Child Assent, and 
Other Considerations: N/A 
 
14.0 Waiver of Participant Signature on Consent Form: N/A 
 
15.0 Waivers and Alterations of Consent Information: N/A 
 
16.0 Financial Compensation: 
Upon completion of the study tasks, the participant will be paid an hourly rate for 
participation ($15/hour). Payment will be made in cash at the conclusion of each 
session. If the participant decides to withdraw from the study before its 
completion, he/she will be paid $15/hour for the time spent. There is also 
dedicated parking space for research participants (at no charge) and an accessible 
entrance to the lab building. 
 
Due to the COVID-19 pandemic, participants will be given the option of being 
compensated at the above rate in the form of a Hyperwallet Virtual Card provided 
by Northwestern University in order to minimize the risk of exposure. The card 
will be issued at the completion of the study visit at which point the participant 
will be emailed instructions for the card activation process. For participants who 
do not have access to email, they will also be given the option of being issued a 
check or a physical gift card for the amount that they are owed. Financial 
compensation will not be withheld in the event of loss or damage to any 
experimental equipment. 
 
 
17.0 Audio/Video Recording/Photography 
 

 
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Audio and video recordings may be obtained during the screening tests and the 
listening tasks. The purpose of the audio/video recordings is to ensure accuracy (a 
second scorer may listen to the recordings and correct any potential errors). The 
recordings will contain only non-identifiable information and will be destroyed 3 
years after the completion of the study. Audio and video recordings will not be 
obtained during earmold impressions and hearing aid fitting. 
 
18.0 Potential Benefits of this Research:  
Participants in this study may not directly benefit from the experiment. The 
findings from this research can result in improvements in clinical decision-making 
for hearing aid fittings and audiological care. Therefore, participants with hearing 
loss seeking hearing aids may benefit in the long-term. Many participants are 
interested in hearing aid research as an opportunity to get information and ask 
questions about hearing aids without sales pressure. All participants will have the 
opportunity to receive counseling at the end of the study, by the investigators or 
the research coordinator, all of whom are also trained and certified audiologists. 
Counseling, if and when provided, will include listening recommendations 
tailored to their individual speech understanding and memory. Participants will 
have the chance to ask questions and receive information about options for their 
hearing loss (outside the study). 
 
19.0 Risks to Participants: 
All study procedures pose minimal risk to participants. There is potential that the 
study task might be boring or repetitive, and therefore if a participant wishes to 
discontinue testing at any point, they may choose to do so without any 
consequence. Listeners who receive poor scores on the cognitive tests may be 
disappointed to learn of their performance. Some listeners may find the sounds 
processed through the hearing aid simulator to be sharp or tinny in comparison to 
their unaided hearing. These are normal and expected consequences of any 
hearing aid fitting. Loudness discomfort levels will be measured and presentation 
levels will be monitored to ensure that levels never become uncomfortable.  
When the earmold impression is taken, participants may experience some 
temporary discomfort or a ticklish feeling as the cotton/foam block is placed into 
the ear canal. Participants may also notice that the impression material is slightly 
cold, or experience a feeling of pressure while the impression material is in your 
ear. Rarely, there can be some minor abrasions to the skin of the ear canal. These 
procedures are routinely used when fitting hearing aids or creating custom 
earplugs and the risks in this study are no higher than the risks that would be 
experienced in an audiology clinic. 
 
The hearing aids and earmolds will only be used for the duration of the 
experiment. The participant is free to remove the hearing aids and/or leave the test 
booth at any time. Participants are encouraged to take breaks and can discontinue 
the study at any time without penalty. If the investigator determines participation 

 
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in the study places a participant at unacceptable risk, enrollment or study tasks 
will not proceed.  
 
Participant confidentiality will be ensured by storing data without subject 
identifiers. Data files are password protected and can only be accessed by 
authorized lab members. Hard copy data are stored in locked file cabinets within a 
restricted-access laboratory space. All study staff complete training in ethical 
procedures for working with human subjects and in HIPAA regulations. 
 
If a research participant decides to withdraw or discontinue study procedures, all 
data collected up to that point can be used by the investigator unless the 
participant indicates that they would like to have their data removed from the 
study. In the event that a participant is removed from the study without their 
consent, compensation will be pro-rated based on the duration the participant 
remained compliant with study tasks and procedures. 
 
In the event that a participant is compensated using the Hyperwallet Virtual Card, 
an account will need to be created using the participant’s name and email address, 
which will link their name to the study. This creates a small additional risk of 
breach of confidentiality. 
 
20.0 Provisions to Protect Participant Privacy and Data 
Confidentiality: 
All experimental procedures will be conducted in the Hearing Aid Lab at 
Northwestern University. The data for this study will include audiometric 
thresholds, age, cognitive measures, speech intelligibility scores, hearing aid 
fitting data, and acoustic measurements. Participant responses recorded through 
the computer interface will be coded and will not contain any identifiable 
information. All data will be de-identified prior to analysis. De-identification will 
take place by assigning a particular code to all data pertaining to one subject. The 
link between the subject code and the subject name will be stored in a password-
protected file on a HIPAA-approved server managed by Northwestern School of 
Communication computer support staff. This information will also be stored on 
the secure REDCap database. Participant identifiers will be stored electronically 
on REDCap in a separate instrument than the study data. REDCap will also be 
used to track study data. All research staff will receive appropriate Human 
Subjects protection training and training regarding confidentiality. Data are only 
accessible by the study staff via password-protected files. Discussion regarding 
subject confidentiality will also be included during regular lab meetings. 
21.0 Data Monitoring Plan to Ensure the Safety of Participants: 
All experimental procedures will be conducted in the Hearing Aid Lab and the 
virtual sound room at Northwestern University. The data for this study will 
include audiological data, age, cognitive measures, and speech intelligibility 
scores, hearing aid fitting data, and acoustic measurements. Participant responses 
recorded by the experimenter through the computer interface will be coded and 

 
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will not contain any identifiable information. Any audio-recording done for the 
purpose of scoring will also be de-identified and will be deleted at the end of the 
experiment. All data will be de-identified prior to analysis. De-identification will 
take place by assigning a particular code to all data pertaining to one subject. The 
same subject code will be used in the hearing aid programming software. The link 
between the subject code and the subject name will be stored in a password-
protected file on a HIPAA-approved server managed by Northwestern School of 
Communication computer support staff. All research staff will receive appropriate 
Human Subjects protection training and training regarding confidentiality. Data 
are only accessible by the study staff via password-protected files. Discussion 
regarding subject confidentiality will also be included during regular lab 
meetings.  
 
The proposed research uses a very low-risk intervention (i.e., hearing aids). The 
investigator(s) will be responsible for ensuring participants’ safety at the time of 
experimentation. If the investigator(s) determine that participation in the study 
places a participant at an unacceptable risk, enrollment or study tasks will not 
proceed. The participants will use the laboratory hearing aids only for the duration 
of the experiment. Therefore, the use of the intervention will always be monitored 
by the experimenter. The co-investigator is responsible for making the ear 
impressions and completing the hearing aid fitting. All testing will be conducted 
by an investigator, the research study coordinator, or a research assistant. The 
research assistant will be supervised by an investigator or the research study 
coordinator. The investigators as well as the research study coordinator are trained 
and licensed audiologists and have several years of experience in conducting 
hearing assessments, hearing aid fitting, and research with adults and are therefore 
qualified for monitoring the study. 
 
22.0 Long-term Data and Specimen Storage and Sharing: N/A 
23.0 Qualifications of Research Team to Conduct the Research: 
Our team has extensive experience in human research and all members are CITI 
(Collaborate Institutional Training Initiative) certified: 
 
o Pamela Souza is a researcher and a licensed audiologist who has more 
than 20 years of experience studying hearing aids and speech perception. 
 
o Varsha Rallapalli is a research assistant professor who has significant 
experience in human research and is also a trained and licensed 
audiologist and a researcher with over six years of human research 
experience. Her research expertise is in the area of speech perception, 
modeling, and hearing aids. 
 
o Kendra Marks is a research study coordinator in the Hearing Aid Lab. She 
is a trained and licensed audiologist and has over eight years of experience 

 
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in hearing testing, hearing aid fitting, and counseling patients with hearing 
loss as well as significant experience in human research.  
 
o Research assistant on the study who will assist with data collection and 
analysis will be a graduate student in audiology who is receiving training 
in assessment and rehabilitation of hearing-impaired individuals. The 
research assistant will also be CITI certified. 
 
References 
1. Blackwell, D.L., Villarroel, M.A., Summary Health Statistics for U.S. Adults: 2016 
National Health Interview Survey, N.C.f.H. Statistics, Editor. 2016. 
2. Kochkin, S., MarkeTrak VII: Patients report improved quality of life with hearing aid 
usage. Hearing Journal, 2011. 64(6): p. 25-32. 
3. Gopinath, B., et al., Incidence and predictors of hearing aid use and ownership 
among older adults with hearing loss. Annals Epidemiology, 2011. 21(7): p. 497-506. 
4. Abrams, H., Kihm, J., An Introduction to MarkeTrak IX: A New Baseline for the 
Hearing Aid Market. Hearing Review, 2015. 22(6): p. 16. 
5. Bainbridge, K.E. and V. Ramachandran, Hearing Aid Use among Older United States 
Adults: The National Health and Nutrition Examination Survey, 2005–2006 and 
2009–2010. Ear and Hearing, 2014. 35(3): p. 289-94. 
6. Dawes, P., et al., Hearing loss and cognition: The role of hearing aids, social 
isolation and depression. PLOS One, 2015. 10(3). 
7. Dawes, P., et al., Hearing-aid use and long-term health outcomes: Hearing handicap, 
mental health, social engagement, cognitive function, physical health, and mortality. 
International Journal of Audiology, 2015A. 54: p. 838-844. 
8. National Academy of Sciences (NAS), Hearing health care services: improving 
access and quality. , in Hearing Health Care for Adults: Priorities for Improving 
Access and Affordability., D. Blazer, Domnitz, S and Liverman, CT, Editor. 2016, 
National Academy of Sciences: Washington, DC. p. 75–148. 
9. Souza, P., et al., Working memory and intelligibility of hearing-aid processed speech. 
Frontiers in Psychology, 2015. 6: p. 526. 
10. Gatehouse, S., G. Naylor, and C. Elberling, Linear and nonlinear hearing aid fittings-
-2. Patterns of candidature. International Journal of Audiology, 2006. 45(3): p. 153-
71. 
11. Ohlenforst, B., P. Souza, and E.N. Macdonald, Exploring the relationship between 
working memory, compressor speed and background noise characteristics. Ear and 
Hearing, 2015. 37: p. 137-143. 
12. Lunner, T. and E. Sundewall-Thorén, Interactions between cognition, compression, 
and listening conditions: Effects on speech-in-noise performance in a two-channel 
hearing aid. Journal of the American Academy of Audiology, 2007. 18(7): p. 604-
617. 
13. Walden, B.E., et al., Effect of signal-to-noise ratio on directional microphone benefit 
and preference. Journal of the American Academy of  Audiology, 2005. 16(9): p. 
662-76. 
14. Ahsan, S.F., et al., Clinical Predictors of Abnormal Magnetic Resonance Imaging 
Findings in Patients With Asymmetric Sensorineural Hearing Loss: Predicting 

 
Page 19 of 19 
HRP-583 / v05062019 
Abnormal MRI in Asymmetric Hearing Loss. JAMA Otolaryngology–Head & Neck 
Surgery, 2015. 141(5): p. 451-456. 
15. Hornsby, B.W., Mueller, H.G., Monosyllabic word testing: Five simple steps to 
improve accuracy and efficiency. AudiologyOnline.com, 2013. 
16. Nasreddine, Z.S., et al., The Montreal Cognitive Assessment, MoCA: a brief 
screening tool for mild cognitive impairment. Journal of the American Geriatrics 
Society, 2005. 53(4): p. 695-699. 
17. Shen, J., et al., Using cognitive screening tests in audiology. American Journal of 
Audiology, 2016. 25(4): p. 319-331. 
18. Rosenthal, S., IEEE: Recommended practices for speech quality measurements. IEEE 
Transactions on Audio and Electroacoustics, 1969. 17: p. 227-46. 
19. Daneman, M. and P.A. Carpenter, Individual differences in working memory and 
reading. Journal of Verbal Learning and Verbal Behavior, 1980. 19(4): p. 450-66. 
20. Ricketts, T., Directivity quantification in hearing aids: fitting and measurement 
effects. Ear and Hearing, 2000. 21(1): p. 45-58. 
21. Klyn, N. A., Robler, S. K., Bogle, J., Alfakir, R., Nielsen, D. W., Griffith, J. W., ... & 
Zapala, D. A. (2019). CEDRA: A tool to help consumers assess risk for ear 
disease. Ear and hearing, 40(6), 1261-1266. 
22. Margolis, R. H., Killion, M. C., Bratt, G. W., & Saly, G. L. (2016). Validation of the 
home hearing test™. Journal of the American Academy of Audiology, 27(5), 416-
420. 
23. Picou, E. M., & Ricketts, T. A. (2017). How directional microphones affect speech 
recognition, listening effort and localisation for listeners with moderate-to-severe 
hearing loss. International journal of audiology, 56(12), 909–918. 
24. Wechsler, D. (1997). WAIS-III: Administration and Scoring Manual: Wechler Adult 
Intelligence Scale (3 ed.). San Antonio, TX: NCS Pearson: Pearson. 
25. Strori, D., & Souza, P. E. (2022). The role of working memory in speech recognition 
by hearing-impaired older listeners: does the task matter?. International journal of 
audiology, 1–9. Advance online publication.