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Neuropsychologia Jul 2023Listening environments contain background sounds that mask speech and lead to communication challenges. Sensitivity to slow acoustic fluctuations in speech can help...
Listening environments contain background sounds that mask speech and lead to communication challenges. Sensitivity to slow acoustic fluctuations in speech can help segregate speech from background noise. Semantic context can also facilitate speech perception in noise, for example, by enabling prediction of upcoming words. However, not much is known about how different degrees of background masking affect the neural processing of acoustic and semantic features during naturalistic speech listening. In the current electroencephalography (EEG) study, participants listened to engaging, spoken stories masked at different levels of multi-talker babble to investigate how neural activity in response to acoustic and semantic features changes with acoustic challenges, and how such effects relate to speech intelligibility. The pattern of neural response amplitudes associated with both acoustic and semantic speech features across masking levels was U-shaped, such that amplitudes were largest for moderate masking levels. This U-shape may be due to increased attentional focus when speech comprehension is challenging, but manageable. The latency of the neural responses increased linearly with increasing background masking, and neural latency change associated with acoustic processing most closely mirrored the changes in speech intelligibility. Finally, tracking responses related to semantic dissimilarity remained robust until severe speech masking (-3 dB SNR). The current study reveals that neural responses to acoustic features are highly sensitive to background masking and decreasing speech intelligibility, whereas neural responses to semantic features are relatively robust, suggesting that individuals track the meaning of the story well even in moderate background sound.
Topics: Humans; Semantics; Perceptual Masking; Noise; Acoustics; Speech Perception; Speech Intelligibility; Acoustic Stimulation
PubMed: 37169066
DOI: 10.1016/j.neuropsychologia.2023.108584 -
NeuroImage Apr 2021Our senses are continuously bombarded with more information than our brain can process up to the level of awareness. The present study aimed to enhance understanding on...
Our senses are continuously bombarded with more information than our brain can process up to the level of awareness. The present study aimed to enhance understanding on how attentional selection shapes conscious access under conditions of rapidly changing input. Using an attention task, EEG, and multivariate decoding of individual target- and distractor-defining features, we specifically examined dynamic changes in the representation of targets and distractors as a function of conscious access and the task-relevance (target or distractor) of the preceding item in the RSVP stream. At the behavioral level, replicating previous work and suggestive of a flexible gating mechanism, we found a significant impairment in conscious access to targets (T2) that were preceded by a target (T1) followed by one or two distractors (i.e., the attentional blink), but striking facilitation of conscious access to targets shown directly after another target (i.e., lag-1 sparing and blink reversal). At the neural level, conscious access to T2 was associated with enhanced early- and late-stage T1 representations and enhanced late-stage D1 representations, and interestingly, could be predicted based on the pattern of EEG activation well before T1 was presented. Yet, across task conditions, we did not find convincing evidence for the notion that conscious access is affected by rapid top-down selection-related modulations of the strength of early sensory representations induced by the preceding visual event. These results cannot easily be explained by existing accounts of how attentional selection shapes conscious access under rapidly changing input conditions, and have important implications for theories of the attentional blink and consciousness more generally.
Topics: Adolescent; Attentional Blink; Brain; Consciousness; Electroencephalography; Female; Humans; Male; Perceptual Masking; Photic Stimulation; Random Allocation; Young Adult
PubMed: 33497774
DOI: 10.1016/j.neuroimage.2021.117789 -
Journal of the American Academy of... Sep 2021There are many counseling and sound therapy approaches to treat tinnitus. Counseling approaches range from providing information using directive or collaborative... (Randomized Controlled Trial)
Randomized Controlled Trial
BACKGROUND
There are many counseling and sound therapy approaches to treat tinnitus. Counseling approaches range from providing information using directive or collaborative approaches. Sound therapies include strategies that use background sounds to totally or partially mask tinnitus to reduce the prominence of or decrease the loudness or annoyance of the tinnitus.
PURPOSE
We evaluated the effectiveness of tinnitus activities treatment (TAT) in two groups, those without hearing aids (HA) and those who were provided with HA. In both groups, comparisons were made among those receiving (1) counseling only, (2) counseling and partial masking, and (3) counseling and total masking.
RESEARCH DESIGN
Participants were provided with HA or not, based on their choice, and then randomly assigned to one of the three groups. The Tinnitus Handicap Questionnaire (THQ) was used as the primary measure.
RESULTS
For those without HA, significant benefits were obtained for 8 out of 22 participants in the counseling group, 8 of 13 in the total masking group, and 8 of 24 in the partial mask group. The average decrease in the THQ was 15% for the counseling group, 25% for the total mask, and 14% for the partial masking group. For those with HA; significant benefits were obtained for 5 of 16 in the counseling group, 3 of 14 in the total mask group, and 6 of 13 in the partial mask group. The average decrease in the THQ score was 12% for counseling, 13% for total masking, and 16% for partial masking. No significant differences among groups were observed.
CONCLUSION
Individual differences were large. Many benefited from their treatment, but some did not. We believe this was likely influenced by their expectations.
Topics: Hearing Aids; Humans; Perceptual Masking; Surveys and Questionnaires; Tinnitus; Treatment Outcome
PubMed: 34965596
DOI: 10.1055/s-0041-1731698 -
Journal of Vision Feb 2022Continuous tracking is a newly developed technique that allows fast and efficient data acquisition by asking participants to "track" a stimulus varying in some property...
Continuous tracking is a newly developed technique that allows fast and efficient data acquisition by asking participants to "track" a stimulus varying in some property (usually position in space). Tracking is a promising paradigm for the investigation of dynamic features of perception and could be particularly well suited for testing ecologically relevant situations difficult to study with classical psychophysical paradigms. The high rate of data collection may be useful in studies on clinical populations and children, who are unable to undergo long testing sessions. In this study, we designed tracking experiments with two novel stimulus features, numerosity and size, proving the feasibility of the technique outside standard object tracking. We went on to develop an ideal observer model that characterizes the results in terms of efficiency of conversion of stimulus strength into responses, and identification of early and late noise sources. Our ideal observer closely modeled results from human participants, providing a generalized framework for the interpretation of tracking data. The proposed model allows to use the tracking paradigm in various perceptual domains, and to study the divergence of human participants from ideal behavior.
Topics: Child; Humans; Models, Psychological; Motion Perception; Perceptual Masking; Space Perception; Visual Perception
PubMed: 35103756
DOI: 10.1167/jov.22.2.3 -
Brain and Behavior Sep 2019The perception of a target stimulus can be impaired by a subsequent mask stimulus, even if they do not overlap temporally or spatially. This "backward masking" is...
INTRODUCTION
The perception of a target stimulus can be impaired by a subsequent mask stimulus, even if they do not overlap temporally or spatially. This "backward masking" is commonly used to modulate a subject's awareness of a target and to characterize the temporal dynamics of vision. Masking is most apparent with brief, low-contrast targets, making detection difficult even in the absence of a mask. Although necessary to investigate the underlying neural mechanisms, evaluating masking phenomena in animal models is particularly challenging, as the task structure and critical stimulus features to be attended must be learned incrementally through rewards and feedback. Despite the increasing popularity of rodents in vision research, it is unclear if they are susceptible to masking illusions.
METHODS
We characterized how spatially surrounding masks affected the detection of sine-wave grating targets.
RESULTS
In humans (n = 5) and rats (n = 7), target detection improved with contrast and was reduced by the presence of a mask. After controlling for biases to respond induced by the presence of the mask, a clear reduction in detectability was caused by masks. This reduction was evident when data were averaged across all animals, but was only individually significant in three animals.
CONCLUSIONS
While perceptual masking occurs in rats, it may be difficult to observe consistently in individual animals because the complexity of the requisite task pushes the limits of their behavioral capabilities. We suggest methods to ensure that masking, and similarly subtle effects, can be reliably characterized in future experiments.
Topics: Adult; Animals; Female; Humans; Male; Models, Animal; Orientation, Spatial; Perceptual Masking; Photic Stimulation; Rats
PubMed: 31444998
DOI: 10.1002/brb3.1368 -
Consciousness and Cognition Jul 2022Visual scenes typically contain redundant information. One mechanism by which the visual system compresses such redundancies is 'redundancy masking' - the reduction of...
Visual scenes typically contain redundant information. One mechanism by which the visual system compresses such redundancies is 'redundancy masking' - the reduction of the perceived number of items in repeating patterns. For example, when presented with three lines in the periphery, observers frequently report only two lines. Redundancy masking is strong in radial arrangements and absent in tangential arrangements. Previous studies suggested that redundancy-masked percepts predominate in stimuli susceptible to redundancy masking. Here, we investigated whether strong redundancy masking is associated with high confidence in perceptual judgements. Observers viewed three to seven radially or tangentially arranged lines at 10° eccentricity. They first indicated the number of lines, and then rated their confidence in their responses. As expected, redundancy masking was strong in radial arrangements and weak in tangential arrangements. Importantly, with radial arrangements, observers were more confident in their responses when redundancy masking occurred (i.e., lower number of lines reported) than when it did not occur (i.e., correct number of lines reported). Hence, observers reported higher confidence for erroneous than for correct judgments. In contrast, with tangential arrangements, observers were similarly confident in their responses whether redundancy masking occurred or not. The inversion of confidence in the radial condition (higher confidence when accuracy was low and lower confidence when accuracy was high) suggests that redundancy-masked appearance trumps 'veridical' perception. The often-reported richness of visual consciousness may partly be due to overconfidence in erroneous judgments in visual scenes that are subject to redundancy masking.
Topics: Consciousness; Humans; Judgment; Perceptual Masking; Visual Perception
PubMed: 35598518
DOI: 10.1016/j.concog.2022.103349 -
Ear and Hearing 2020When one ear of an individual can hear significantly better than the other ear, evaluating the worse ear with loud probe tones may require delivering masking noise to...
OBJECTIVES
When one ear of an individual can hear significantly better than the other ear, evaluating the worse ear with loud probe tones may require delivering masking noise to the better ear to prevent the probe tones from inadvertently being heard by the better ear. Current masking protocols are confusing, laborious, and time consuming. Adding a standardized masking protocol to an active machine learning audiogram procedure could potentially alleviate all of these drawbacks by dynamically adapting the masking as needed for each individual. The goal of this study is to determine the accuracy and efficiency of automated machine learning masking for obtaining true hearing thresholds.
DESIGN
Dynamically masked automated audiograms were collected for 29 participants between the ages of 21 and 83 (mean 43, SD 20) with a wide range of hearing abilities. Normal-hearing listeners were given unmasked and masked machine learning audiogram tests. Listeners with hearing loss were given a standard audiogram test by an audiologist, with masking stimuli added as clinically determined, followed by a masked machine learning audiogram test. The hearing thresholds estimated for each pair of techniques were compared at standard audiogram frequencies (i.e., 0.25, 0.5, 1, 2, 4, 8 kHz).
RESULTS
Masked and unmasked machine learning audiogram threshold estimates matched each other well in normal-hearing listeners, with a mean absolute difference between threshold estimates of 3.4 dB. Masked machine learning audiogram thresholds also matched well the thresholds determined by a conventional masking procedure, with a mean absolute difference between threshold estimates for listeners with low asymmetry and high asymmetry between the ears, respectively, of 4.9 and 2.6 dB. Notably, out of 6200 masked machine learning audiogram tone deliveries for this study, no instances of tones detected by the nontest ear were documented. The machine learning methods were also generally faster than the manual methods, and for some listeners, substantially so.
CONCLUSIONS
Dynamically masked audiograms achieve accurate true threshold estimates and reduce test time compared with current clinical masking procedures. Dynamic masking is a compelling alternative to the methods currently used to evaluate individuals with highly asymmetric hearing, yet can also be used effectively and efficiently for anyone.
Topics: Adult; Aged; Aged, 80 and over; Audiometry; Audiometry, Pure-Tone; Auditory Threshold; Hearing; Hearing Loss; Humans; Machine Learning; Middle Aged; Perceptual Masking; Young Adult
PubMed: 33136643
DOI: 10.1097/AUD.0000000000000891 -
The Journal of the Acoustical Society... Feb 2020Negative masking (NM) is a ubiquitous finding in near-"threshold" psychophysics in which the detectability of a near-threshold signal improves when added to a copy of...
Negative masking (NM) is a ubiquitous finding in near-"threshold" psychophysics in which the detectability of a near-threshold signal improves when added to a copy of itself, i.e., a pedestal or masker. One interpretation of NM suggests that the pedestal acts as an informative cue, thereby reducing uncertainty and improving performance relative to detection in its absence. The purpose of this study was to test this hypothesis. Intensity discrimination thresholds were measured for 100-ms, 1000-Hz near-threshold tones. In the reference condition, thresholds were measured in quiet (no masker other than the pedestal). In comparison conditions, thresholds were measured in the presence of one of two additional maskers: a notched-noise masker or a random-frequency multitone masker. The additional maskers were intended to cause different amounts of uncertainty and, in turn, to differentially influence NM. The results were generally consistent with an uncertainty-based interpretation of NM: NM was found both in quiet and in notched-noise, yet it was eliminated by the multitone masker. A competing interpretation of NM based on nonlinear transduction does not account for all of the results. Profile analysis may have been a factor in performance and this suggests that NM may be attributable to, or influenced by, multiple mechanisms.
Topics: Auditory Threshold; Noise; Perceptual Masking; Psychophysics; Uncertainty
PubMed: 32113297
DOI: 10.1121/10.0000652 -
The Journal of the Acoustical Society... Jul 2023Masking can reduce the efficiency of communication and prey and predator detection. Most underwater sounds fluctuate in amplitude, which may influence the amount of...
Masking can reduce the efficiency of communication and prey and predator detection. Most underwater sounds fluctuate in amplitude, which may influence the amount of masking experienced by marine mammals. The hearing thresholds of two harbor seals for tonal sweeps (centered at 4 and 32 kHz) masked by sinusoidal amplitude modulated (SAM) Gaussian one-third octave noise bands centered around the narrow-band test sweep frequencies, were studied with a psychoacoustic technique. Masking was assessed in relation to signal duration, (500, 1000, and 2000 ms) and masker level, at eight amplitude modulation rates (1-90 Hz). Masking release (MR) due to SAM compared thresholds in modulated and unmodulated maskers. Unmodulated maskers resulted in critical ratios of 21 dB at 4 kHz and 31 dB at 32 kHz. Masked thresholds were similarly affected by SAM rate with the lowest thresholds and the largest MR being observed for SAM rates of 1 and 2 Hz at higher masker levels. MR was higher for 32-kHz maskers than for 4-kHz maskers. Increasing signal duration from 500 ms to 2000 ms had minimal effect on MR. The results are discussed with respect to MR resulting from envelope variation and the impact of noise in the environment on target signal detection.
Topics: Animals; Auditory Threshold; Phoca; Perceptual Masking; Noise; Hearing; Cetacea
PubMed: 37409781
DOI: 10.1121/10.0019631 -
The Journal of the Acoustical Society... Jan 2023The detectability of target amplitude modulation (AM) can be reduced by masker AM in the same carrier-frequency region. It can be reduced even further, however, if the...
The detectability of target amplitude modulation (AM) can be reduced by masker AM in the same carrier-frequency region. It can be reduced even further, however, if the masker-AM rate is uncertain [Conroy and Kidd, J. Acoust. Soc. Am. 149, 3665-3673 (2021)]. This study examined the effectiveness of contextual cues in reducing this latter, uncertainty-related effect (modulation informational masking). Observers were tasked with detecting fixed-rate target sinusoidal amplitude modulation (SAM) in the presence of masker SAM applied simultaneously to the same broadband-noise carrier. A single-interval, two-alternative forced-choice detection procedure was used to measure sensitivity for the target SAM; masker-AM-rate uncertainty was created by randomly selecting the AM rate of the masker SAM on each trial. Relative to an uncued condition, a pretrial cue to the masker SAM significantly improved sensitivity for the target SAM; a cue to the target SAM, however, did not. The delay between the cue-interval offset and trial-interval onset did not affect the size of the masker-cue benefit, suggesting that adaptation of the masker SAM was not responsible. A simple model of within-AM-channel masking captured important trends in the psychophysical data, suggesting that reduced masker-AM-rate uncertainty may have played a relatively minor role in the masker-cue benefit.
Topics: Auditory Threshold; Perceptual Masking; Cues; Uncertainty
PubMed: 36732267
DOI: 10.1121/10.0016867