Comparing Outcomes With the Cloud-based and Portable Versions of an Open-source Hearing Aid.
Phase: NA
Conditions: Hearing Loss, Hearing Loss, Sensorineural
Sponsor: Northwestern University

 
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Official Title: Open-source Hearing Aid Platform Comparisons 
 
NCT number: NCT05693610 
 
Document date: Approved in continuing review by IRB on 
03.16.2024 
 

 
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STUDY TITLE: 
Validating outcomes with an open-source hearing aid. 
 
PRINCIPAL INVESTIGATOR: 
Name: Varsha Rallapalli, Au.D., Ph.D., CCC-A 
Department: Communication Sciences and Disorders (School of Communication) 
 
VERSION DATE: 
6.16.2022 
 
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 via 
direct award or a sub-
award (e.g., NIH, NSF, other 
federal agencies or 
departments) 
 
☒ 
NIH (R44DC020406) 
 
 
1.0 
Purpose and rationale of the study: 
Hearing loss (HL) is an invisible disability affecting 360 million people worldwide. In 
the United States, 75% of individuals over the age of 70 have HL [1]. The consequences of 

 
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untreated HL and its downstream effects have been a topic of active clinical research  and 
include reduced quality of life, increased risk of falls, cognitive decline, dementia, and 
Alzheimer’s, [2]–[5]. Despite tremendous advances in modern digital hearing aids (HAs) 
[6] and the potential health benefits of their use, only one in three individuals with HL 
owns a HA [1]. Two of the most cited reasons for low HA adoption are the lack of 
perceived benefit in real-world environments (e.g., noisy environments such as 
restaurants) and limited access due to high cost [7]–[10].  Overcoming these HA adoption 
hurdles has been stymied by the proprietary nature of commercial hearing aids, which 
make it nearly impossible for audiology researchers to understand and evaluate the 
innerworkings of commercial HAs in real-world conditions. Moreover, signal processing 
implementations across HA manufacturers can be very different for a given technology 
[11], [12] making it a challenge to compare across devices and prescribe the best 
implementation suitable for an individual listener. To circumvent these proprietary 
constraints, researchers often resort to laboratory simulations of HAs [13]–[16] that may 
be restricted to certain forms of signal processing. The drawback of this approach is the 
inadequate representation of the features in a commercial HA (e.g., open-ear acoustics, 
microphone location, etc.) that often interact with the signal processing [17]. 
Alternatively, to capture effects of wearable HAs, researchers may use commercial 
devices as a “black box” and rely on external metrics as proxies to characterize the effects 
of signal processing [18], [19]. Unfortunately, this approach can reduce the scientific rigor 
of experiments because of the inability to precisely describe and manipulate signal 
processing in the HA. In order to advance hearing healthcare and enable HA innovations 
that could improve quality and cost, thus increasing adoption of hearing aids, audiology 
researchers need validated open-source HA platforms that mimic commercial HAs in form 
and function. 
 
The open-source speech processing platform (OSP) was developed in response to 
call from National Institute on Deafness and Other Communication Disorders (NIDCD) 
for new open-source platforms [20], [21].The OSP serves the following functions: 1) 
provides researchers complete control for long-term stability for experiments, 2) 
Researchers can configure the hearing aid processing features and investigate 
interactions among these features, 3) OSP provides an integrated research environment 
on a single platform to streamline and support an efficient research workflow. The 
purpose of this project is to advance the academic proofs of concepts for researcher 
tools successfully completed with previous R21/R33 and R01 funding into working 
audiology researcher tools (Aim 1), outcomes assessment tools (Aim 2) and ecological 
momentary assessment (EMA) tools (Aim 3 [not included in this behavioral study]) to 
address the need for an open-source HA with a full range of signal processing 
capabilities and complete researcher control. 
 
Specific Aims pertaining to the behavioral study are 1) Refine and validate hearing 
research tools and advance OSP hardware/software to commercial grade (for 
researchers). This aim will investigate interactions among OSP parameters such as 
spatial processing, compression release times, noise managenment, etc. 2) Develop and 

 
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validate outcomes assessment tools to enable researchers to present acoustic stimuli 
and log users’ responses, along with other information such as reaction time, number of 
stimulus repetitions to achieve reliable behavioral responses.  
 
The study is a within-subjects design that allows for comparison of outcomes within 
the same participant. Experiment 1: We will compare baseline performance(unaided) 
and performance with the OSP (aided) for adults with hearing loss. We will measure 
performance in the laboratory using common clinical tests of speech understanding in 
noise as well as noise acceptance. We will test aided performance with different hearing 
aid settings. The hearing aid settings may vary with regard to compression and noise 
management. Statistical analyses will use a repeated measures model to control for 
correlation between outcomes for the same participant. 
 
Experiment 2: To validate the capability of the OSP to assess listener outcomes, we 
will also compare aided speech discrimination ability in quiet and in noise for two test 
modes: OSP assessment tool (stimulus presentation controlled by participant & 
responses collected directly from the participant on the OSP) versus conventional 
(stimulus presentation controlled on an external program by experimenter & paper-and-
pencil responses provided by participant). Statistical analyses methods will quantify 
agreement, correlation, and association (linear regression) between outcomes from the 
two test modes.  
 
In both experiments, each participant will be presented with all the test conditions 
(hearing aid settings or test modes) in a laboratory setting. The order of presentation of 
the test conditions will be randomized and counterbalanced across participants. 
 
2.0 
Enrollment Criteria (who can be in your study and who would not 
be eligible to participate in your study): 
Inclusion Criteria: 
- >= 18 years of age; any sex 
- Sensorineural hearing loss with pure-tone thresholds between 25-85 dB HL at 
octave frequencies between 250 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 
- Non English-speaking or non-native English speaking 

 
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For the purposes of test validation and calibration, we may also enroll a small 
group (n=50) of listeners with normal hearing, defined as pure-tone thresholds 
of 25 dB HL or less at octave frequencies between 250 and 3000 Hz. 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. 
 
3.0 
Sample Size: 
The proposed study will recruit 100 participants (based on power analysis) with 
bilateral symmetric sensorineural HL in the mild to severe range, over a 2-year 
period. Each experiment will recruit approximately 40 participants (additional 10 
account for pilot testing and attrition). 
 
Experiment 1 (Aim 1) 
We assume type I error rates of 2.5% for tests of contrasts between repeated 
measures within individuals. We anticipate N=40 participants will suffice to detect 
moderate effects of d=0.5 with 80% power. Effects of this size translate to 0.71 dB 
points for QuickSIN and 2.6 for ANL. These are smaller than critical differences 
identified for QuickSIN (2.7 dB) [22] and ANL (6 dB) [23]. A smaller sample size 
would provide 80% power to detect larger effects (see Table A), though even if we 
fall short of our recruitment and data collection goals, we will still be well-powered 
to detect meaningful effects in Aim-1. 
Table A. Sample sizes & effect sizes for Aim-1 
Sample Size Difference (d) QuickSIN Diff. ANL Diff. 
30 
0.59 
0.82 
4.12 
35 
0.54 
0.76 
3.79 
40 
0.50 
0.71 
3.53 
 
Experiment 2 (Aim 2) 
We will report 95% confidence intervals for the ICC and Pearson correlations, 
which will have similar widths (see Table B). A sample size of N=40 would allow for 
narrow confidence intervals for large ICCs and correlations; and ICC≥0.87 or 
correlation >0.87 would have a 95% confidence interval width <0.15. Smaller ICCs 
would have larger confidence interval widths; an ICC or correlation of 0.7 would 
have a 95% confidence interval width of 0.33. 
 

 
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Table B. Pearson correlations, ICC, and 
corresponding confidence interval (CI) 
widths for Aim-2 
Correlation 
Cor. CI ICC 
ICC CI 
0.5 
0.48 0.5 
0.47 
0.7 
0.33 0.7 
0.33 
0.8 
0.24 0.8 
0.23 
0.9 
0.13 0.9 
0.13 
 
 
4.0 
Recruitment and Screening Methods: 
 
Recruitment process: 
The proposed study will recruit 100 adults (18 years or older) over a two-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 audiology clinics, local 
community, local senior centers, and local Hearing Loss Association of America 
(HLAA) chapter. Recruitment methods will include flyers and brochures to the 
department and local audiology clinics, local senior centers, and the local HLAA 
chapter; advertisements in local social media boards and newspapers; flyers on 
bulletin boards throughout the Northwestern campus.  
 
Screening methods: 
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 [24] 
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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Interested participants will be contacted by the research staff via phone/email as 
preferred by the potential participant. At this time, the participant will be 
provided with basic information regarding study procedures and inclusion 
criteria. The lab manager will be the primary point of contact to coordinate all 
recruitment and scheduling, and Dr. Rallapalli (PI) will be available as needed. 
 
*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 [28]) 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: 
All participants must be native speakers of English because our outcome 
measures include speech recognition of English sentences or words. Therefore, 
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 > 85 dB 
HL at any frequency between 250-3000 Hz 
Monosyllabic 
word recognition 
Percentage of phonetically-
balanced words repeated in quiet 
at a comfortable loudness.  
Evidence of significant asymmetry between 
ears [25] 
Montreal 
Cognitive 
Assessment 
(MoCA) [26] 
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 [27] (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/tablet screen. MoCA (above) 
involves identifying/copying visual objects. 
We will exclude subjects who fail vision 
screening. 

 
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proficiency in English is required for the validity of the results. Our study 
population is adults with hearing loss. Therefore, we will include individuals with 
sensorineural hearing loss with pure-tone thresholds between 25-85 dB HL at 
octave frequencies between 250 and 3000 Hz. This meets the criteria for a mild 
to severe hearing loss. This is the typical range of hearing loss for which 
individuals seek hearing aids, and 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 screening and experiment involve visual tasks. The participants should 
be in general good health (based on self-report). 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. 
Participants who do not pass the cognitive screening test (< 23 on the Montreal 
Cognitive Assessment [26], [27]) will also be excluded because cognitive 
impairments may confound the results and are beyond the scope of this study.  
 
 
5.0 
Research Locations: 
 
The proposed work will be conducted within the Hearing Aid Lab (Director: 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 is 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.  
 
Participant research visits may be conducted remotely. Remote participation 
allows a more diverse group of people to participate, especially those with 
limited or intermittent access to transportation, mobility challenges, or health 
concerns where that can be addressed by limiting in person contact, especially in 
light of covid 19. Remote visits may be conducted 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 

 
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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. 
 
6.0 
Multi-site Research (research that involves external collaborating 
institutions and individuals):  
The current study is a behavioral research study being conducted to validate 
outcomes with an open-speech platform. This study is being conducted under a 
subaward to Northwestern University (subaward PI: Dr. Rallapalli), and the main 
SBIR grant will be awarded to Dr. Harinath Garudadri (Nadi, LLC).  
 
All the human subjects research work proposed here will be conducted at a 
single-site, i.e., at Northwestern University. Communication of results and 
findings will only be done with de-identified data. When sharing information, de-
identified data will be exchanged via secure FTP. In addition to be being de-
identified, all data will be stored in a secure password protected database or on 
REDcap, and will only be accessible to study staff at Northwestern University.  
 
7.0 
International Research (where data collection will occur outside the 
United States and U.S. territories, including online activities): NA 
 
8.0 
Procedures Involved: 
 
Please check the boxes for all applicable data collection procedures you plan to use: 
☐One-on-one interviews 
☐Focus Groups 
☐Questionnaires/surveys 
☐Analysis of secondary data (medical record data, educational records, government or 
private sector datasets, etc.) 
☐Ethnographic observation 
☐Physiological measurements (e.g., EEG, EKG, MRI) 
☐Biospecimen collection (saliva samples, blood draws, hair samples, etc.) 
☐Mobile applications/data collection devices (e.g., Fitbits, actigraphs, etc.) 
☒Behavioral decision making tasks (e.g., puzzles, interactive games, etc.) 
☐Physical activities such as walking and other forms of exercise 
☐Other procedures (briefly list types of procedures here if not covered by the check-
boxes above): ______________________________________________ 
 
 
The proposed research will measure aided speech perception outcomes for hearing-
impaired listeners under laboratory conditions, with a combination of hearing aid 

 
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settings in quiet and noisy conditions. The study will use the OSP to provide various 
combinations of hearing aid signal processing. Test procedures including stimuli and 
outcome measures are described below.  
 
Data collection for each experiment will include the following steps per participant: 
Session 
Aim 1 (Exp. 1) 
Approx. Duration 
Aim 2 (Exp. 2) 
Approx. Duration 
Session 1 
Candidacy 
assessment 
60-80 mins 
Candidacy 
assessment 
60-80 mins 
Baseline/Unaided 
outcome 
measurement 
(QuickSIN, ANL) 
30 mins 
Earmold 
impression (if 
needed) 
15-20 mins 
Earmold 
impression (if 
needed) 
15-20 mins 
Session 2 
Earmold + OSP 
Fitting 
45-60 mins 
Earmold + OSP 
Fitting 
45-60 mins 
Aided Outcome 
measurement 
(QuickSIN, ANL) 
60 mins 
Aided Outcome 
measurement 
(MRT) 
60 mins 
Session 2 may take place ~7-10 days after session 1 to allow for time taken for the 
custom earmold order to be received.  
 
Open-source speech processing platform (OSP): 
The OSP will be used to provide amplification to the participant. The OSP mimics the 
functionality of a hearing aid in that it will process sound in real-time. The OSP has 
wearable earpieces or calibrated headphones to deliver the processed sound to the 
ears. However, unlike a commercial hearing aid, the processing takes places via a 
computer simulation of a hearing aid (portable or fixed) rather than within the housing 
that rests on the participants ears and also contains the microphones. The OSP allows 
flexible adjustments beyond what is available in commercial hearing aids, and ensures 
adequate scientific rigor. Different signal processing features in the hearing aid, 
including spatial processing and noise reduction will be varied across test conditions. 
Clinically realistic settings will be used. The amount of amplification with the hearing aid 
will be customized for each listener based on a validated prescription. The hearing aids 
will be fit to a foam/ear tip or a custom earmold. These are standard clinical procedures 
as described below. 
 
The OSP will be used for the duration of the experiment in a lab setting under the 
supervision of the experimenter. The OSP will be returned the experimenter at the end 
of a session.  
 
Stimuli: 

 
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Recorded speech materials (words, sentences, or passages) will be presented. These 
speech materials will be combined with speech-shaped noise or 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) or a comfortable level for the 
listener.  
 
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.  
 
Outcome measures: 
Speech recognition: The recorded speech materials that have been electronically 
processed and mixed with multi-talker babble or speech-shaped noise, 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 or headphones 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.  
 
QuickSIN: The test measures speech recognition ability in noise. Participants will listen 
to and repeat recorded sentences mixed with noise. Scoring is determined by the 
number of words repeated correctly. Scores range from 0 to 25.5 dB SNR loss (a lower 
score indicates better speech recognition ability in noise). The task is expected to take 
10-15 minutes for each test condition and up to 30 minutes per session. The task 

 
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duration includes time for instructions and practice. The outcome measure will be 
completed under experiment 1. 
 
Modified Rhyme Test (MRT): The test is a measure of word-discrimination ability. 
Participants will select a word out of a choice of six rhyming words. The words may be in 
quiet or mixed with background noise and will be presented through the hearing 
aid/speakers/earphones. Participants may be asked to record their responses on paper 
or via button/mouse click on a computer or tablet screen. Scores will be based on 
percentage of words identified correctly (range: 0-100%). A higher score indicates better 
word-discrimination ability. Scores for phonetic-level errors and reaction times for 
responses may also be reported with the OSP assessment tool. The task is expected to 
take 30 minutes for each test condition and up to 60 minutes per session. The outcome 
measure will be completed under experiment 2. 
 
Acceptable Noise Level Test (ANL): Participants will indicate the level of noise that is 
acceptable while listening to running speech. Scoring is determined based on the 
difference between the listener's most comfortable level for speech and the highest 
background noise level they are willing to accept. A smaller score indicates better noise 
acceptance. The task is expected to take 10-15 minutes for each test condition and up to 
30 minutes per session. The task duration includes time for instructions and practice. 
The outcome measure will be completed under experiment 1. 
 
Preference and sound quality: Sound quality and listener preferences are critical 
component of successful hearing aid outcomes. Multiple dimensions of sound quality 
may be assessed using rating scales. Participants will listen to speech or sentences that 
have been electronically processed, and rate each sentence for overall quality, 
pleasantness, clarity, noisiness, loudness, and preference. Alternatively, participants 
may be presented with pairs of electronically processed speech (words, sentences or 
paragraphs) and they may be asked to select whichever one they prefer. The speech 
may be presented in quiet or mixed with different levels and types of pre-recorded 
noise (such as multiple talkers, babble, and other environmental noise). Ratings will be 
provided using a graphical user interface on a tablet or computer monitor (using a 
touchscreen, keyboard or mouse). The task may take upto 60 minutes and may be 
conducted in a separate session (e.g., session 3) if needed.  
 
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 repeating the speech so that their responses 
may be scored later by the experimenter (also see section 15). The participant will be 
guided with on screen instructions and may reach the experimenter via an intercom at 
any time.  
 
Acoustic measurements: After the completion of experiment by the participant, de-
identified hearing aid fitting data may be retrieved from the hearing aid in order to 

 
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record output on an acoustic manikin or a sound level meter 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. This part of the experiment does not directly involve the participant and 
will only be conducted with de-identified materials.  
 
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.  
 

 
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9.0 
Research with Vulnerable Populations: NA 
 
10.0 Incomplete Disclosure or Deception: NA 
 
11.0 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.  
 
Virtual consent may be obtained as an alternative (e.g., remote participation). 
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 

 
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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 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.  
 
12.0 Waiver of Participant Signature on Consent Form: NA 
 
13.0 Waivers and Alterations of Consent Information: NA 
 
14.0 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. 
 
Participants may be given the option of being compensated at the above rate in 
the form of a Hyperwallet Virtual Card provided by Northwestern University. 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. 
 
15.0 Audio/Video Recording/Photography 
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 

 
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(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. 
 
16.0 Potential Benefits of this Research:  
Participants in this study may not directly benefit from the experiment. The 
importance of this research lies in the potential to generate innovative and 
evidence-based solutions to increase access to hearing healthcare. 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). 
17.0 Potential 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 MoCA may be 
disappointed to learn of their performance. Some listeners may find the sounds 
processed through the OSP 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 

 
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participation 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. 
 
18.0 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 perception 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. 
 
19.0 Data Monitoring Plan to Ensure the Safety of Participants: 
All experimental procedures will be conducted in the Hearing Aid Lab or the 
virtual sound room at Northwestern University. The data for this study will 

 
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include audiological data, age, cognitive measures, and speech perception 
scores, hearing aid fitting data, and acoustic measurements. Participant 
responses recorded by the experimenter through the computer interface will be 
coded and 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 will be responsible for ensuring participants’ safety at the time of 
experimentation. If the investigator determines that participation in the study 
places a participant at an unacceptable risk, enrollment or study tasks will not 
proceed. The participants will use the OSP only for the duration of the 
experiment. Therefore, the use of the OSP will always be monitored by the 
experimenter. A trained audiologist is responsible for making the ear 
impressions and completing the OSP fitting. All testing will be conducted by an 
investigator, an audiologist, the research study coordinator, or a research 
assistant. The research assistant will be supervised by an investigator or the 
research study coordinator. The investigator 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. 
 
20.0 Long-term Data and Specimen Storage and Sharing: N/A 
 
21.0 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 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 ten years of human research 
experience. Her research expertise is in the area of speech perception, 
modeling, and hearing aids. 

 
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o Kendra Marks is a research study coordinator in the Hearing Aid Lab. She 
is a trained and licensed audiologist and has over ten years of experience 
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. 
 
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