Biology subjects

Johnsrude, I.

Publications and source records attributed to Johnsrude, I..

8 recordsLinked to original sources

bioRxiv2026

Fatigue-related changes in value-based decision-making during listening are associated with increased frontal cortical activation

Hearing aid users commonly report listening-related fatigue, which may contribute to disengagement from demanding listening situations and negative psychosocial outcomes. Hearing rehabilitation currently lacks strategies to mitigate listening fatigue, partly because fatigue build-up and its consequences are difficult to measure beyond self-report. This study investigated whether value-based listening decisions and associated frontal cortical activity are modulated by fatigue. Thirty hearing aid users completed a one-hour listening paradigm while cortical hemodynamic activity was measured using functional near-infrared spectroscopy (fNIRS). On each trial, participants decided whether to engage in listening or rest based on an offer defined by expected task difficulty and reward, and rated their momentary fatigue. Fatigue ratings increased over time, and unsuccessful listening trials were associated with larger subsequent increases in fatigue, suggesting that performance contributed to changes in self-reported fatigue. Listen-versus-rest decisions followed the expected effort-reward trade-off, with participants more likely to accept offers that provided higher rewards and lower listening demands. Over the course of the experiment, participants became less likely to accept listening offers; however, neither time on task nor subjective fatigue altered the weighting of reward and difficulty. In contrast, frontal cortical activation during evaluation of accepted offers increased over time for high-difficulty offers with low or medium rewards. Follow-up analyses indicated that frontal oxygenation and listening decisions were more strongly associated with time on task than with subjective fatigue ratings. Together, these findings suggest that behavioral and neural measures obtained before listening capture fatigue-related processes beyond self-report, providing a basis for identifying and potentially addressing fatigue in hearing rehabilitation.

neuroscience↗

bioRxiv2026

The Listening Effort Profile of Eye Movements: Easy, Difficult, and Impossible Speech Comprehension

Speech comprehension in noisy environments often requires cognitive effort, but listeners may disengage when comprehension becomes impossible. Eye movements have recently emerged as a promising new measure of listening effort, but it remains unclear whether eye movements are sensitive to the full effort profile across easy, difficult, and impossible speech comprehension. Across four experiments, participants listened to sentences at easy, difficult, and impossible levels of multi-talker background babble while pupil size and eye movements were recorded. Pupil size generally followed the expected inverted u-shaped effort profile: low for easy speech, maximal for difficult but still intelligible speech and lower again for impossible speech, although this pattern partly reflected sustained, condition-specific differences and not only sentence-evoked responses. Gaze dispersion - measuring the spread of eye movements - decreased with high temporal selectivity during difficult relative to easy and impossible speech, indicating reduced eye movements during active, effortful listening. However, gaze dispersion was also lower, but less temporally selective, during impossible compared to easy listening, especially in non-baseline-corrected analyses, suggesting that reduced eye movements do not index listening effort uniquely. Instead, eye movements appear to reflect both attentional engagement during difficult listening and disengagement or inward attention when meaningful listening is no longer possible. These findings indicate that pupil size and eye movements provide complementary indices of listening-related cognition, and highlight the integration of listening, cognition, and motor systems.

neuroscience↗

bioRxiv2025

Neural signatures of engagement and event segmentation during story listening in background noise

Speech in everyday life is often masked by background noise, making comprehension effortful. Characterizing brain activity patterns when individuals listen to masked speech can help clarify the mechanisms underlying such effort. However, most previous research has focused on neural activity related to short, disconnected sentences that little resemble the more continuous, story-like spoken speech individuals typically encounter. In the current study, we used functional magnetic resonance imaging (fMRI) in humans (both sexes) to investigate how neural signatures of story listening change in the presence of masking by 12-talker babble noise. We show that, as speech masking increases, spatial and temporal activation patterns in auditory regions become more idiosyncratic to each listener. In contrast, spatial (and to some extent temporal) activity patterns in brain networks linked to effort (e.g. cinguloopercular network involving the anterior insula and anterior cingulate) are more similar across listeners when speech is highly masked and less intelligible, suggesting shared neural processes. Moreover, at times during stories when one meaningful event ended and another began, neural activation increased over extensive regions in frontal, parietal, and medial cortices. This event-boundary response appeared little affected by background noise, suggesting that listeners process meaningful units and, in turn, the gist in naturalistic, continuous speech even when it is masked somewhat by background noise. Overall, the current data may indicate that people stay engaged and cognitive processes associated with naturalistic speech processing remain intact under moderate levels of background noise, whereas auditory processing becomes more idiosyncratic to each listener. Significance statementThis functional imaging study investigates how neural signatures of story listening change in the presence of masking multi-talker babble noise. We show that, as speech masking increases, auditory activity patterns become more idiosyncratic to each listener. Spatial activation patterns in effort-related regions (anterior insula, cingulate) become more similar across listeners when speech is strongly masked, indicating shared neural representations. Neural activation also increased at times when one meaningful story event ended and another began. This event-boundary response appeared little affected by moderate levels of background noise, suggesting that listeners process meaningful units in continuous speech even as background babble reduces speech intelligibility. The data indicate that many cognitive processes associated with listening to spoken stories remain intact under background noise.

neuroscience↗

bioRxiv2025

Pupil responses indicate task-relevance and (unsuccessful) inhibition of background sounds during a dual, continuous listening task

Auditory attention can be voluntarily directed towards a sound source or automatically captured by background sounds, which may be either relevant, such that the listener shifts their attention to them, or irrelevant such that the listener tries to ignore or inhibit them. The ability to switch focus to a relevant sound source while inhibiting an irrelevant one requires attentional control and is crucial for navigating busy auditory scenes. Objective measures of attentional control could be beneficial in clinical contexts, such as fitting hearing aids. In a dual-task paradigm, we investigated whether pupil responses reflect relevance-dependent attentional selectivity. Participants with self-reported normal hearing (N = 21, Age: 27 to 66 years, pure tone average: -4 to +26 dB HL) listened to continuous speech from the front (primary task) while background sounds, consisting of cue names followed immediately by two-digit numbers, were presented from the left and right. The participant was told that one side, either right or left, was relevant and the other, irrelevant. The secondary task involved memorizing and later recognizing numbers from the relevant side. We observed increased pupil responses to sounds from the relevant side compared to the irrelevant side, indicating selectivity. Exploratory analysis showed that participants who exhibited stronger selectivity recognized more numbers correctly. Interestingly, pupil responses did not differ between hits and misses, but a stronger response to stream confusions versus correct rejections was found, suggesting that participants were more challenged by inhibiting irrelevant sounds than shifting attention to relevant sounds. In sum, our findings demonstrate that pupillometry provides valuable insights into attentional control abilities.

neuroscience↗

bioRxiv2024

Fidelity of focal sound source reproduction by higher (9th) order ambisonics and perceptual effects of reproduction errors

Higher-order ambisonic rendering is an increasingly common soundscape reproduction technique that, in theory, enables presentation of virtual sounds at nearly any location in 3D space, relatively unconstrained by the veridical locations of loudspeakers. We evaluated whether 3D sound reproduction through a 9th-order ambisonic loudspeaker array was indeed sufficiently accurate to probe the limits of human spatial perception. We first estimated minimum audible angles for human listeners for a variety of reference points on the horizontal plane. We demonstrated that the system can reproduce sounds with a spatial resolution that is equal or superior to the limits of human acuity, at least on the horizontal plane at the front. Importantly, the resolution of ambisonic reproduction appeared equivalent for regions of the system with high and low loudspeaker density. We also estimated localization cues at the same locations and showed that although localization cues for low-frequency components were well preserved, they were somewhat distorted for components above 4000 Hz. Finally, we provide evidence that these high-frequency distortions can serve elevation cues by human listeners. In summary, we showed that a 9th order ambisonic system is able to render highly focal sound sources, and that high-frequency reproduction distortions may introduce unwanted localization cues.

neuroscience↗

bioRxiv2023

Salience-dependent disruption of sustained auditory attention can be inferred from evoked pupil responses and neural tracking of task-irrelevant sounds

Stimulus-driven attention allows us to react to relevant stimuli (and imminent danger!) outside our current focus of attention. But irrelevant stimuli can also disrupt attention; for example, during listening to speech. The degree to which sound captures attention is called salience, which can be estimated by existing, behaviorally validated, computational models (Huang & Elhilali, 2017). Here we examined whether neurophysiological responses to task-irrelevant sounds indicate the degree of distraction during a sustained-listening task and how much this depends on individual hearing thresholds. N = 47 Danish-speaking adults (28/19 female/male; mean age: 60.1, SD: 15.9 years) with heterogenous hearing thresholds (PTA; mean: 25.5, SD: 18.0 dbHL) listened to continuous speech while one-second-long, task-irrelevant natural sounds (distractors) of varying computed salience were presented at unpredictable times and locations. Eye tracking and electroencephalography were used to estimate pupil response and neural tracking, respectively. The task-irrelevant sounds evoked a consistent pupil response (PR), distractor-tracking (DT) and a drop of target-tracking ({Delta}TT), and statistical modelling of these three measures within subjects showed that all three are enhanced for sounds with higher computed salience. Participants with larger PR showed a stronger drop in target tracking ({Delta}TT) and performed worse in target speech comprehension. We conclude that distraction can be inferred from neurophysiological responses to task-irrelevant stimuli. These results are a first step towards neurophysiological assessment of attention dynamics during continuous listening, with potential applications in hearing-care diagnostics. Significance statementSuccessful speech-in-noise comprehension in daily life does not only depend on the acuity of the auditory input, but also cognitive factors like attentional control. Being able to measure distraction-dependent neurophysiological responses to peripheral, task-irrelevant stimuli would enable monitoring the extent to which the attentional focus is instantaneously captured away from a target under sustained attention. Here we show that especially pupil response and neural tracking of distractor sounds reflect the degree to which people with both normal and elevated hearing thresholds are distracted. Such a measure could be used to non-invasively track the focus of attention and thus could find application in hearing care diagnostics, where cognitive factors like attentional control are being increasingly recognized as important.

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bioRxiv2021

Synchronized Neural Activity Indexes Engagement with Spoken Stories under Acoustic Masking

Older people with hearing problems often experience difficulties understanding speech in the presence of background sound. As a result, they may disengage in social situations, which has been associated with negative psychosocial health outcomes. Measuring listening (dis-)engagement during challenging listening situations has received little attention thus far. We recruit young, normal-hearing human adults (both sexes) and investigate how speech intelligibility and engagement during naturalistic story listening is affected by the level of acoustic masking (12-talker babble) at different signal-to-noise ratios (SNRs). In Experiment 1, we observed that word-report scores were above 80% for all but the lowest SNR (-3 dB SNR) we tested, at which performance dropped to 54%. In Experiment 2, we calculated inter-subject correlation (ISC) using electroencephalography (EEG) data to identify dynamic spatial patterns of shared neural activity evoked by the stories. ISC has previously been used as a neural measure of participants engagement with naturalistic materials. Our results show that ISC was stable across all but the lowest SNRs, despite reduced speech intelligibility. Comparing ISC and intelligibility demonstrated that word-report performance declined more strongly with decreasing SNR compared to ISC. Our measure of neural engagement suggests that individuals remain engaged in story listening despite missing words due to background noise. Our work provides a potentially fruitful approach to investigate listener engagement with naturalistic, spoken stories that may be used to investigate (dis)engagement in older adults with hearing impairment.

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bioRxiv2020

Cortical Responses to the Amplitude Envelopes of Sounds Change with Age

Many older listeners have difficulty understanding speech in noise, when cues to speech-sound identity are less redundant. The amplitude envelope of speech fluctuates dramatically over time, and features such as the rate of amplitude change at onsets (attack) and offsets (decay) signal critical information about the identity of speech sounds. Aging is also thought to be accompanied by increases in cortical excitability, which may differentially alter sensitivity to envelope dynamics. Here, we recorded electroencephalography in younger and older human adults (of both sexes) to investigate how aging affects neural synchronization to 4-Hz amplitude-modulated noises with different envelope shapes (ramped: slow attack & sharp decay; damped: sharp attack & slow decay). We observed that subcortical responses did not differ between age groups, whereas older compared to younger adults exhibited larger cortical responses to sound onsets, consistent with an increase in auditory cortical excitability. Neural activity in older adults synchronized more strongly with rapid-onset, slow-offset (damped) envelopes, was less sinusoidal, and more peaked. Younger adults demonstrated the opposite pattern, showing stronger synchronization with slow-onset, rapid-offset (ramped) envelopes, as well as a more sinusoidal neural response shape. The current results suggest that age-related changes in the excitability of auditory cortex alter responses to envelope dynamics. This may be part of the reason why older adults experience difficulty understanding speech in noise. Significance StatementMany middle aged and older adults report difficulty understanding speech when there is background noise, which can trigger social withdrawal and negative psychosocial health outcomes. The difficulty may be related to age-related changes in how the brain processes temporal sound features. We tested younger and older people on their sensitivity to different envelope shapes, using EEG. Our results demonstrate that aging is associated with heightened sensitivity to sounds with a sharp attack and gradual decay, and sharper neural responses that deviate from the sinusoidal features of the stimulus, perhaps reflecting increased excitability in the aged auditory cortex. Altered responses to temporal sound features may be part of the reason why older adults often experience difficulty understanding speech in social situations.

neuroscience↗