EPOS BrainAdapt™
An Auditory Memory Study
The effect of noise attenuation onmemory recall

Scientific Whitepaper2023

Scientific Whitepaper

Scientific Whitepaper

Introduction
This whitepaper presents theresults of a clinical study thatinvestigated the benefits ofnoise damping technology
used in EPOS Enterprise andGaming audio solutions. The
aim was to demonstrate how
damping effects the listening
effort exerted by the study’s
participants.

2In both professional and personal contexts, we often need to understand speech andremember what is said to perform at our best. However, in today’s world with distractions
abound, this can be difficult.
Humans have limited cognitive capacity, so when we devote cognitive resources to listening, i.e., when recognizing speech, we will have a reduced capacity to perform othertasks, such as memory recall. If we listen to speech through headsets and speakers withpoor audio quality, our ability to listen will be challenged even further.
This whitepaper presents the results of a clinical study that investigated the benefits ofnoise damping technology used in EPOS Enterprise and Gaming audio solutions. Theaim was to demonstrate how damping effects the listening effort exerted by the study’sparticipants.
This type of in-depth scientific research has been a key element in the developmentof audio solutions built on EPOS BrainAdapt™ technology, which supports the brain’s
natural way of processing sound (Christiansen and Ng, 2022). The custom-made components, acoustics and sophisticated algorithms that go into EPOS solutions ensure
optimized cognitive performance, even in challenging sound environments.

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Scientific Whitepaper

Scientific Whitepaper

Scientific Background
EPOS product innovation is driven by psychoacoustic research
In the EPOS product innovation process, we start by defining the sound profile thatsupports the best cognitive performance in specific use cases. To ensure that EPOSsolutions provide the most balanced, clear, and natural soundscape possible, we draw
on more than a decade of research into how the brain perceives sound and how thebrain’s cognitive load can be lowered in various sound situations.
As we move into product development, we implement fine-tuned acoustics and sophisticated algorithms into our solutions. We look at the product holistically, integratetechnical features and the right set of custom-made components to provide the best
conditions for your brain.
Finally, before launch, we conduct psychoacoustic research in collaboration with theDemant Group to validate that EPOS users obtain the cognitive benefit intended. The
following pages present the results of a recent study that will help EPOS continue
deliver superior audio and video solutions with audio designed for the brain.

The technology tested in this study is featured in the following EPOS products:• IMPACT 1060 ANC• IMPACT 1060T ANC• IMPACT 1061 ANC• IMPACT 1061T ANC• ADAPT 600 Series• GTW 270 Hybrid• H3PRO Hybrid• H6PRO Closed

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In our first scientific whitepaper (Christiansen & Ng, 2022), we concluded that noisedamping has a positive effect on speech intelligibility and required listening effort. In thiswhitepaper, we continue to explore the benefits of the EPOS noise damping in terms ofmemory recall performance.
This whitepaper focuses on the results of the Sentence final-Word Identification andRecall (SWIR) test which was conducted at the same time as the studies described inChristiansen & Ng (2022) and Jonsson et al. (2022). The SWIR test is designed to measure the resources devoted to listening as well as memory for speech, which is crucial for
responding and reacting during communication.
Noise attenuation technology in hearing solutions can enhance recall performance byfreeing up cognitive resources that would otherwise have been allocated to speech
recognition (Ng et al., 2013). For listening tasks requiring the participants to immediately
report back the sentence, such as the investigation reported in Christiansen & Ng (2022),
an increase in task-evoked pupil responses is associated with increased listening effort.
Previous studies found that for tasks involving both listening and remembering what isbeing said, an increase in baseline pupil dilation accompanied by better overall recall
performance reflects higher memory effort due to speech encoding into memory.

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The Aim of the Study

Scientific Whitepaper

Results
1. SWIR Test

The aim of this investigation is to study the effect of noise attenuating technology on
the dynamics of pupil responses during a speech recall task. Both recall performanceand pupil responses were examined.

Materials and Methods

Word Identification Performance.
Significantly more words were correctly repeated with noise attenuation (mean 99.7%,SE 0.2%) in comparison to without noise attenuation (mean 96.2%, SE 1.3%) (p < 0.01).
Recall performance
When the average recall performance was calculated based on the total number of
to-be-recalled words in a list (i.e., seven words), the participants recalled significantly
more words with noise attenuation (mean 71.43%, SE 4.7%) than without (mean 64.8%,SE 3.8%) (p < 0.05; see Figure 1). This corresponds to a percentage point differenceof 6.7, or alternatively a 10.3% increase in performance with noise attenuation, which isequivalent to half a word out of a list.
When the average performance was calculated based on the total number of words
identified (i.e., word identification performance), the results showed a similar pattern(mean 71.7%, SE 4.7% with noise attenuation, mean 68.9%, SE 4.1% without noise
attenuation).

The study method, including the details of the participants, study setup, the specificationof the noise attenuation, data analysis including the pupil responses can be found on
page 7 to page 11 in Christiansen & Ng (2022).

Recall Performance (%)

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The SWIR test (Ng et al., 2013), which was also referred to as the load block in
Christiansen & Ng (2022), was administered. The tasks were to 1) identify and verbally
repeat the final word after listening to each sentence, and 2) recall all final words when alist of seven sentences finishes. There were two test conditions: with and without noise
attenuation. All sentence-in-noise stimuli were preprocessed. For each condition, sevenlists of sentences were presented in a four-talker babble noise.

*8070605040

w/o Noise Attenuation

Noise Attenuation

Figure 1: Average recall performance in test conditions with and without Noise Attenuation.
Error bars represent standard errors.

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Scientific Whitepaper

2. Pupil Responses
Figure 2 shows the aggregated pupil traces obtained across all participants for eachtest condition. For each trial (sentence), we extracted two features: the baseline pupil
dilation (BPD) and the mean pupil dilation (MPD). We applied linear fits to the datapoints across a list (7 points) for each feature. The slopes fits of BPD and MPD werethen obtained for each participant (Bönitz et al., 2021).

Aggregated curves within trials x conditions
Trial 1

Trial 3

Trial 4

Trial 5

Trial 6

Trial 7

Time (s)Time (s)Time (s)Time (s)Time (s)Time (s)Time (s)Noise Attenuation

w/o Noise Attenuation

MDP

Pupil Dilatation [mm]BDP

Trial 2

Figure 2:. Pupil traces aggregated within trial (sentence) and test conditions (blue = with noise attenuation, red = without noiseattenuation) across participants. The aggregated pupil traces are relative to the list baseline. Time 0s (the dotted line) indicates thesentence onset. The two features – the baseline pupil dilation (BPD) and mean pupil dilation (MPD) – are indicated in Trial 1. The
shaded area indicates standard error.

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Scientific Whitepaper

In this investigation, we define BPD as an indication of the state of arousal including
memory effort, and the BPD slope indicates the modulation of memory effort
throughout the list. MPD is defined as listening effort, and the MPD slope indicatesthe dynamic change in listening effort thoughout the list/over the course of the seventrials.
The analyses showed that the BPD slope significantly increased (p < 0.05; Figure3) and the MPD slope significantly decreased when noise attenuation was applied(p < 0.01; Figure 4).

**0,040,5BPD Slope (mm/sentence)

BPD Slope (mm/sentence)*0,40,30,20,10-0,020w/o Noise Attenuation

Noise Attenuation

Figure 3: Increased BPD slope with noise attenuation than without. Error bars represent standard errors.

100,02w/o Noise Attenuation

Noise Attenuation

Figure 4: Decreased MPD slope with noise attenuation than without. Error bars represent standard errors.

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Scientific Whitepaper

Conclusions

Implications

To summarize, noise attenuation improved recall performance by 10%. This means thatthe listener is able to remember, on average, 0.5 words more out of 7 words.

Humans have limited cognitive capacity when cognitive resources are devoted torecognizing (i.e., listening), responding and reacting to speech. Figure 5 conceptualizes
how noise affects cognitive resource allocation in relation to a person’s cognitive
capacity, and how the person can benefit from an effective noise attenuation
technology.

When we look at the pupil responses while listening to the SWIR test lists, the mean
pupil dilation (MPD) slope with noise attenuation decreased, suggesting less listening
effort throughout a list. This is in line with the results reported in Christiansen & Ng
(2022). The baseline pupil dilation (BPD) captures the cognitive resources allocatedduring speech encoding in memory. The increase in BPD slope with noise attenuation
indicates higher memory effort. This corroborates with better recall performance inthis investigation.
These findings suggest that reduced listening effort liberates cognitive resourcesthat can be used for speech processing and encoding of information into long-term
memory (Micula et al., 2022). In other words, noise attenuation can liberate cognitive
resources that would have been used for listening effort which are instead used formemory.

1. A person listening in quiet and in noise.
Listening goes from easy to difficult, increasing the resources that are devoted (henceincreased listening effort). This also means less and less resources are available to beallocated for remembering what is being heard.
2. A person listening in noise with noise attenuation.
With an effective noise attenuation system, the person would be able to spend moreresources on remembering. This is particularly crucial when the pressure is on, and oneneeds to have this extra capacity at their disposal.
au, T., & corpus for competing-speech studies. The Journal of the Acoustical Society of America, 135(1), 407–420. https://doi.
org/10.1121/1.4835935

This study is just one example of decades of psychoacoustic research conducted by
the Demant Group, of which is EPOS is proud to be a part. The learnings collected inthis study and others, including a recent study of the benefits of noise dampening, areapplied in ongoing development of EPOS BrainAdapt™ solutions, which are designed
to support the brain’s natural way of processing sound. To learn more about EPOS
solutions and the science behind them, visit eposaudio.com/brainadapt. , h., Dau, T., &Cognitive resources allocated to:

Listening

Other tasksPerson in quiet

A10%better memory recall** 10% better memory recall as indicated through the results of the SWIR test

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Person in noise

B

Person in noisewith noise attenuation

Figure 5: Schematic representations of cognitive resource allocation in different noise conditions.
Inspired by Lunner et al. (2009).

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References
Bönitz, H., Lunner, T., Finke, M., Fiedler, L., Lyxell, B., Riis, S. K., Ng, E., Valdes, A. L.,
Büchner, A., & Wendt, D. (2021). How do we allocate our resources when listening andmemorizing speech in noise? A pupillometry study. Ear and hearing, 42(4), 846-859.
Christiansen, T., & Ng, E. H. N. (2022). EPOS BrainAdaptTM New Evidence: The effectsof noise attenuation on listening effort and arousal. EPOS Scientific Whitepaper.
Jonsson, S., Larsen, E., Christiansen, T., Ng, E., & Micula, A. (2022, June 12-15). The effects of noise attenuation on listening effort and arousal [Poster presentation]. The 6thInternational Conference on Cognitive Hearing Science for Communication, Linköping,
Sweden. https://chscom2022.se/homeLunner, T., Rudner, M., & Rönnberg, J. (2009). Cognition and hearing aids. Scandinavian journal of psychology, 50(5), 395-403.
Micula, A., Rönnberg, J., & Ng, E. (2022, August 10-14). More is more: Physiologicalmarkers of successful effort [Poster presentation]. International Hearing Aid Research
Conference. Tahoe City, California. https://ihcon.org/Ng, E. H. N., Rudner, M., Lunner, T., Pedersen, M. S., & Rönnberg, J. (2013). Effects ofnoise and working memory capacity on memory processing of speech for hearing-aidusers. International journal of audiology. 52(7):433-41.

Editors of the issue:Torben Christiansen, Director of Technology, EPOS
Elaine Hoi Ning Ng Principal Researcher, Centre for Applied Audiology Research, Oticon A/S14