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Journal of the Association For Research... Feb 2023Auditory stream segregation and informational masking were investigated in brain-lesioned individuals, age-matched controls with no neurological disease, and young...
Auditory stream segregation and informational masking were investigated in brain-lesioned individuals, age-matched controls with no neurological disease, and young college-age students. A psychophysical paradigm known as rhythmic masking release (RMR) was used to examine the ability of participants to identify a change in the rhythmic sequence of 20-ms Gaussian noise bursts presented through headphones and filtered through generalized head-related transfer functions to produce the percept of an externalized auditory image (i.e., a 3D virtual reality sound). The target rhythm was temporally interleaved with a masker sequence comprising similar noise bursts in a manner that resulted in a uniform sequence with no information remaining about the target rhythm when the target and masker were presented from the same location (an impossible task). Spatially separating the target and masker sequences allowed participants to determine if there was a change in the target rhythm midway during its presentation. RMR thresholds were defined as the minimum spatial separation between target and masker sequences that resulted in 70.7% correct-performance level in a single-interval 2-alternative forced-choice adaptive tracking procedure. The main findings were (1) significantly higher RMR thresholds for individuals with brain lesions (especially those with damage to parietal areas) and (2) a left-right spatial asymmetry in performance for lesion (but not control) participants. These findings contribute to a better understanding of spatiotemporal relations in informational masking and the neural bases of auditory scene analysis.
Topics: Humans; Perceptual Masking; Noise; Aging; Brain; Auditory Threshold
PubMed: 36471207
DOI: 10.1007/s10162-022-00877-9 -
ELife Jan 2022Can direct stimulation of primate V1 substitute for a visual stimulus and mimic its perceptual effect? To address this question, we developed an optical-genetic toolkit...
Can direct stimulation of primate V1 substitute for a visual stimulus and mimic its perceptual effect? To address this question, we developed an optical-genetic toolkit to 'read' neural population responses using widefield calcium imaging, while simultaneously using optogenetics to 'write' neural responses into V1 of behaving macaques. We focused on the phenomenon of visual masking, where detection of a dim target is significantly reduced by a co-localized medium-brightness mask (Cornsweet and Pinsker, 1965; Whittle and Swanston, 1974). Using our toolkit, we tested whether V1 optogenetic stimulation can recapitulate the perceptual masking effect of a visual mask. We find that, similar to a visual mask, low-power optostimulation can significantly reduce visual detection sensitivity, that a sublinear interaction between visual- and optogenetic-evoked V1 responses could account for this perceptual effect, and that these neural and behavioral effects are spatially selective. Our toolkit and results open the door for further exploration of perceptual substitutions by direct stimulation of sensory cortex.
Topics: Animals; Macaca mulatta; Male; Neurons; Optogenetics; Perceptual Masking; Photic Stimulation; Proof of Concept Study; Visual Cortex; Visual Perception
PubMed: 34982033
DOI: 10.7554/eLife.68393 -
Scientific Reports Dec 2021Sensory cortical mechanisms combine auditory or visual features into perceived objects. This is difficult in noisy or cluttered environments. Knowing that individuals...
Sensory cortical mechanisms combine auditory or visual features into perceived objects. This is difficult in noisy or cluttered environments. Knowing that individuals vary greatly in their susceptibility to clutter, we wondered whether there might be a relation between an individual's auditory and visual susceptibilities to clutter. In auditory masking, background sound makes spoken words unrecognizable. When masking arises due to interference at central auditory processing stages, beyond the cochlea, it is called informational masking. A strikingly similar phenomenon in vision, called visual crowding, occurs when nearby clutter makes a target object unrecognizable, despite being resolved at the retina. We here compare susceptibilities to auditory informational masking and visual crowding in the same participants. Surprisingly, across participants, we find a negative correlation (R = -0.7) between susceptibility to informational masking and crowding: Participants who have low susceptibility to auditory clutter tend to have high susceptibility to visual clutter, and vice versa. This reveals a tradeoff in the brain between auditory and visual processing.
Topics: Adult; Attention; Auditory Perception; Brain; Crowding; Female; Humans; Male; Noise; Perceptual Masking; Vision, Ocular; Visual Perception; Young Adult
PubMed: 34876580
DOI: 10.1038/s41598-021-00328-0 -
International Journal of Audiology Mar 2023The purpose of this study was to 1) characterise word recognition in a speech masker for preschoolers tested using closed-set, forced-choice procedures and 2) better...
OBJECTIVE
The purpose of this study was to 1) characterise word recognition in a speech masker for preschoolers tested using closed-set, forced-choice procedures and 2) better understand the stimulus and listener factors affecting performance.
DESIGN
Speech recognition thresholds (SRTs) in a two-talker masker were evaluated using a picture-pointing response with two sets of disyllabic target words. ChEgSS words were previously developed for children ≥5 years of age, and simple words were developed for preschoolers. Familiarisation ensured accurate identification of target words before testing.
STUDY SAMPLE
Participants were 3- and 4-year olds ( = 21) and young adults ( = 10) with normal hearing.
RESULTS
Preschoolers and adults had significantly lower SRTs for the simple words than the ChEgSS words, and lower SRTs for early-acquired than later-acquired ChEgSS words. For both word sets, SRTs were approximately 11-dB higher for preschoolers than adults, and child age was associated with SRTs. Preschoolers' receptive vocabulary size predicted performance for ChEgSS words but not simple words.
CONCLUSIONS
Preschoolers were more susceptible to speech-in-speech masking than adults, with a similar child-adult difference for the ChEgSS and simple words. Effects of receptive vocabulary in preschoolers' recognition of ChEgSS words indicate that vocabulary size is an important consideration, even when using closed-set methods.
Topics: Young Adult; Humans; Perceptual Masking; Speech; Speech Perception; Recognition, Psychology; Vocabulary
PubMed: 35184649
DOI: 10.1080/14992027.2022.2035833 -
Neuropsychologia Apr 2024Ambient sound can mask acoustic signals. The current study addressed how echolocation in people is affected by masking sound, and the role played by type of sound and...
Ambient sound can mask acoustic signals. The current study addressed how echolocation in people is affected by masking sound, and the role played by type of sound and spatial (i.e. binaural) similarity. We also investigated the role played by blindness and long-term experience with echolocation, by testing echolocation experts, as well as blind and sighted people new to echolocation. Results were obtained in two echolocation tasks where participants listened to binaural recordings of echolocation and masking sounds, and either localized echoes in azimuth or discriminated echo audibility. Echolocation and masking sounds could be either clicks or broad band noise. An adaptive staircase method was used to adjust signal-to-noise ratios (SNRs) based on participants' responses. When target and masker had the same binaural cues (i.e. both were monoaural sounds), people performed better (i.e. had lower SNRs) when target and masker used different types of sound (e.g. clicks in noise-masker or noise in clicks-masker), as compared to when target and masker used the same type of sound (e.g. clicks in click-, or noise in noise-masker). A very different pattern of results was observed when masker and target differed in their binaural cues, in which case people always performed better when clicks were the masker, regardless of type of emission used. Further, direct comparison between conditions with and without binaural difference revealed binaural release from masking only when clicks were used as emissions and masker, but not otherwise (i.e. when noise was used as masker or emission). This suggests that echolocation with clicks or noise may differ in their sensitivity to binaural cues. We observed the same pattern of results for echolocation experts, and blind and sighted people new to echolocation, suggesting a limited role played by long-term experience or blindness. In addition to generating novel predictions for future work, the findings also inform instruction in echolocation for people who are blind or sighted.
Topics: Animals; Humans; Sound Localization; Blindness; Noise; Acoustics; Cues; Perceptual Masking; Acoustic Stimulation
PubMed: 38342179
DOI: 10.1016/j.neuropsychologia.2024.108822 -
The Journal of the Acoustical Society... Feb 2022Recent work has suggested that there may be specialized mechanisms in the auditory system for coding spectrotemporal modulations (STMs), tuned to different combinations...
Recent work has suggested that there may be specialized mechanisms in the auditory system for coding spectrotemporal modulations (STMs), tuned to different combinations of spectral modulation frequency, temporal modulation frequency, and STM sweep direction. The current study sought evidence of such mechanisms using a psychophysical forward masking paradigm. The detectability of a target comprising upward sweeping STMs was measured following the presentation of modulated maskers applied to the same carrier. Four maskers were tested, which had either (1) the same spectral modulation frequency as the target but a flat temporal envelope, (2) the same temporal modulation frequency as the target but a flat spectral envelope, (3) the same spectral and temporal modulation frequencies as the target but the opposite sweep direction (downward sweeping STMs), or (4) the same spectral and temporal modulation frequencies as the target and the same sweep direction (upward sweeping STMs). Forward masking was greatest for the masker fully matched to the target (4), intermediate for the masker with the opposite sweep direction (3), and negligible for the other two (1, 2). These findings are consistent with the suggestion that the detectability of the target was mediated by an STM-specific coding mechanism with sweep-direction selectivity.
Topics: Acoustic Stimulation; Auditory Threshold; Perceptual Masking
PubMed: 35232084
DOI: 10.1121/10.0009404 -
JASA Express Letters Dec 2022Amplitude-modulation (AM) forward masking was measured for listeners with normal hearing and sensorineural hearing loss at 4000 and 1000 Hz, using continuous and...
Amplitude-modulation (AM) forward masking was measured for listeners with normal hearing and sensorineural hearing loss at 4000 and 1000 Hz, using continuous and noncontinuous masker and signal carriers, respectively. A low-fluctuation noise (LFN) carrier was used for the "continuous carrier" conditions. An unmodulated low-fluctuation noise (U-LFN), an unmodulated Gaussian noise (U-GN), and an amplitude-modulation low-fluctuation noise (AM-LFN) were maskers for the "noncontinuous carrier" conditions. As predicted, U-GN yielded more masking than U-LFN and similar masking to AM-LFN, suggesting that U-GN resulted in AM forward masking. Contrary to predictions, no differences in masked thresholds were observed between listener groups.
Topics: Humans; Acoustic Stimulation; Auditory Threshold; Deafness; Hearing Loss; Hearing Loss, Sensorineural; Perceptual Masking
PubMed: 36586961
DOI: 10.1121/10.0015315 -
The Journal of the Acoustical Society... May 2021A contralateral "cue" tone presented in continuous broadband noise both lowers the threshold of a signal tone by guiding attention to it and raises its threshold by...
A contralateral "cue" tone presented in continuous broadband noise both lowers the threshold of a signal tone by guiding attention to it and raises its threshold by interference. Here, signal tones were fixed in duration (40 ms, 52 ms with ramps), frequency (1500 Hz), timing, and level, so attention did not need guidance. Interference by contralateral cues was studied in relation to cue-signal proximity, cue-signal temporal overlap, and cue-signal order (cue after: backward interference, BI; or cue first: forward interference, FI). Cues, also ramped, were 12 dB above the signal level. Long cues (300 or 600 ms) raised thresholds by 5.3 dB when the signal and cue overlapped and by 5.1 dB in FI and 3.2 dB in BI when cues and signals were separated by 40 ms. Short cues (40 ms) raised thresholds by 4.5 dB in FI and 4.0 dB in BI for separations of 7 to 40 ms, but by ∼13 dB when simultaneous and in phase. FI and BI are comparable in magnitude and hardly increase when the signal is close in time to abrupt cue transients. These results do not support the notion that masking of the signal is due to the contralateral cue onset/offset transient response. Instead, sluggish attention or temporal integration may explain contralateral proximal interference.
Topics: Acoustic Stimulation; Auditory Threshold; Cues; Perceptual Masking; Time Factors
PubMed: 34241123
DOI: 10.1121/10.0004786 -
Communications Biology Aug 2022Ambient noise is a major constraint on acoustic communication in both animals and humans. One mechanism to overcome this problem is Spatial Release from Masking (SRM),...
Ambient noise is a major constraint on acoustic communication in both animals and humans. One mechanism to overcome this problem is Spatial Release from Masking (SRM), the ability to distinguish a target sound signal from masking noise when both sources are spatially separated. SRM is well described in humans but has been poorly explored in animals. Although laboratory tests with trained individuals have suggested that SRM may be a widespread ability in vertebrates, it may play a limited role in natural environments. Here we combine field experiments with investigations in captivity to test whether crocodilians experience SRM. We show that 2 species of crocodilians are able to use SRM in their natural habitat and that it quickly becomes effective for small angles between the target signal source and the noise source, becoming maximal when the angle exceeds 15. Crocodiles can therefore take advantage of SRM to improve sound scene analysis and the detection of biologically relevant signals.
Topics: Acoustic Stimulation; Acoustics; Alligators and Crocodiles; Animals; Humans; Noise; Perceptual Masking
PubMed: 36008592
DOI: 10.1038/s42003-022-03799-7 -
Attention, Perception & Psychophysics Jul 2022The linguistic similarity hypothesis states that it is more difficult to segregate target and masker speech when they are linguistically similar. For example,...
The linguistic similarity hypothesis states that it is more difficult to segregate target and masker speech when they are linguistically similar. For example, recognition of English target speech should be more impaired by the presence of Dutch masking speech than Mandarin masking speech because Dutch and English are more linguistically similar than Mandarin and English. Across four experiments, English target speech was consistently recognized more poorly when presented in English masking speech than in silence, speech-shaped noise, or an unintelligible masker (i.e., Dutch or Mandarin). However, we found no evidence for graded masking effects-Dutch did not impair performance more than Mandarin in any experiment, despite 650 participants being tested. This general pattern was consistent when using both a cross-modal paradigm (in which target speech was lipread and maskers were presented aurally; Experiments 1a and 1b) and an auditory-only paradigm (in which both the targets and maskers were presented aurally; Experiments 2a and 2b). These findings suggest that the linguistic similarity hypothesis should be refined to reflect the existing evidence: There is greater release from masking when the masker language differs from the target speech than when it is the same as the target speech. However, evidence that unintelligible maskers impair speech identification to a greater extent when they are more linguistically similar to the target language remains elusive.
Topics: Humans; Language; Linguistics; Perceptual Masking; Speech; Speech Perception
PubMed: 35474415
DOI: 10.3758/s13414-022-02486-3