Asynchronous glimpsing of speech: spread of masking and task set-size.
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ABSTRACT:
SUBMITTER: Ozmeral EJ
PROVIDER: S-EPMC3427370 | biostudies-other | 2012 Aug
REPOSITORIES: biostudies-other
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Project description:People with schizophrenia have impairments of target-speech recognition (TSR) in noisy environments with multiple people talking. This study investigated whether the TSR impairment in schizophrenia is associated with their impaired auditory working memory or certain psychotic symptoms. Thirty participants with schizophrenia (mean age = 35.2 ± 12.7 years) and 30 demographics-matched healthy controls (mean age = 32.9 ± 10.9 years) were tested for their TSR against a two-talker-speech masker. Auditory working memory and memory capacity were evaluated using the Paced Auditory Serial Addition Test (PASAT) and Digit Span Test. Psychotic symptoms were evaluated using the Positive and Negative Syndrome Scale (PANSS). The results showed that participants with schizophrenia had higher TSR threshold (i.e., poorer TSR performance) and poorer PASAT scores than their healthy controls. Moreover, positive correlations (with age, sex, educational years, ill-duration, and dosage of antipsychotics controlled as covariates) were revealed between the TSR threshold and the PANSS-positive syndrome (especially delusion), and between the TSR threshold and the PANSS-negative syndrome (especially lack of spontaneity in speech and passive-apathetic-social withdraw). However, neither the PASAT nor the forward digit span exhibited significant correlations with the TSR. This study provides evidence that the TSR impairment (i.e., augmented vulnerability to informational speech masking), which reflects disorganization of speech information processing (inability in either inhibiting unrelated speech signals or capturing the wanted speech signals), is specifically associated with the severity of delusion, poverty of speech, and hypobulia, suggesting the potential value of the TSR impairment used for predicting certain core symptoms of schizophrenia.
| S-EPMC6007045 | biostudies-literature
Project description:The brain is adaptive. The speed of propagation through air, and of low-level sensory processing, differs markedly between auditory and visual stimuli; yet the brain can adapt to compensate for the resulting cross-modal delays. Studies investigating temporal recalibration to audiovisual speech have used prolonged adaptation procedures, suggesting that adaptation is sluggish. Here, we show that adaptation to asynchronous audiovisual speech occurs rapidly. Participants viewed a brief clip of an actor pronouncing a single syllable. The voice was either advanced or delayed relative to the corresponding lip movements, and participants were asked to make a synchrony judgement. Although we did not use an explicit adaptation procedure, we demonstrate rapid recalibration based on a single audiovisual event. We find that the point of subjective simultaneity on each trial is highly contingent upon the modality order of the preceding trial. We find compelling evidence that rapid recalibration generalizes across different stimuli, and different actors. Finally, we demonstrate that rapid recalibration occurs even when auditory and visual events clearly belong to different actors. These results suggest that rapid temporal recalibration to audiovisual speech is primarily mediated by basic temporal factors, rather than higher-order factors such as perceived simultaneity and source identity.
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Project description:ObjectivesThis study aimed to evaluate the informational component of speech-on-speech masking. Speech perception in the presence of a competing talker involves not only informational masking (IM) but also a number of masking processes involving interaction of masker and target energy in the auditory periphery. Such peripherally generated masking can be eliminated by presenting the target and masker in opposite ears (dichotically). However, this also reduces IM by providing listeners with lateralization cues that support spatial release from masking (SRM). In tonal sequences, IM can be isolated by rapidly switching the lateralization of dichotic target and masker streams across the ears, presumably producing ambiguous spatial percepts that interfere with SRM. However, it is not clear whether this technique works with speech materials.DesignSpeech reception thresholds (SRTs) were measured in 17 young normal-hearing adults for sentences produced by a female talker in the presence of a competing male talker under three different conditions: diotic (target and masker in both ears), dichotic, and dichotic but switching the target and masker streams across the ears. Because switching rate and signal coherence were expected to influence the amount of IM observed, these two factors varied across conditions. When switches occurred, they were either at word boundaries or periodically (every 116 msec) and either with or without a brief gap (84 msec) at every switch point. In addition, SRTs were measured in a quiet condition to rule out audibility as a limiting factor.ResultsSRTs were poorer for the four switching dichotic conditions than for the nonswitching dichotic condition, but better than for the diotic condition. Periodic switches without gaps resulted in the worst SRTs compared to the other switch conditions, thus maximizing IM.ConclusionsThese findings suggest that periodically switching the target and masker streams across the ears (without gaps) was the most efficient in disrupting SRM. Thus, this approach can be used in experiments that seek a relatively pure measure of IM, and could be readily extended to translational research.
| S-EPMC6856419 | biostudies-literature
Project description:HypothesisThe hypothesis tested was that forward masking of the speech-evoked auditory brainstem response (sABR) increases peak latency as an inverse function of masker-signal interval (Δt), and that the overall persistence of forward masking is age dependent.BackgroundOlder listeners exhibit deficits in forward masking. If forward-masked sABRs provide an objective measure of the susceptibility of speech sounds to prior stimulation, then this provides a novel approach to examining the age dependence of temporal processing.MethodsA /da/ stimulus forward masked by speech-shaped noise (Δt = 4-64 ms) was used to measure sABRs in 10 younger and nine older participants. Forward masking of subsegments of the /da/ stimulus (Δt = 16 ms) and click trains (Δt = 0-64 ms) was also measured.ResultsForward-masked sABRs from young participants showed an increase in latency with decreasing Δt for the initial peak. Latency shifts for later peaks were smaller and more uniform. None of the peak latencies returned to baseline by Δt = 64 ms. Forward-masked /da/ subsegments showed peak latency shifts that did not depend simply on peak position, while forward-masked click trains showed latency shifts that were dependent on click position. The sABRs from older adults were less robust but confirmed the viability of the approach.ConclusionForward masking of the sABR provides an objective measure of the susceptibility of the auditory system to prior stimulation. Failure of recovery functions to return to baseline suggests an interaction between forward masking by the prior masker and temporal effects within the stimulus itself.
| S-EPMC5823537 | biostudies-literature
Project description:Adaptive signal-to-noise ratio (SNR) tracking is often used to measure speech reception in noise. Because SNR varies with performance using this method, data interpretation can be confounded when measuring an SNR-dependent effect such as the fluctuating-masker benefit (FMB) (the intelligibility improvement afforded by brief dips in the masker level). One way to overcome this confound, and allow FMB comparisons across listener groups with different stationary-noise performance, is to adjust the response set size to equalize performance across groups at a fixed SNR. However, this technique is only valid under the assumption that changes in set size have the same effect on percentage-correct performance for different masker types. This assumption was tested by measuring nonsense-syllable identification for normal-hearing listeners as a function of SNR, set size and masker (stationary noise, 4- and 32-Hz modulated noise and an interfering talker). Set-size adjustment had the same impact on performance scores for all maskers, confirming the independence of FMB (at matched SNRs) and set size. These results, along with those of a second experiment evaluating an adaptive set-size algorithm to adjust performance levels, establish set size as an efficient and effective tool to adjust baseline performance when comparing effects of masker fluctuations between listener groups.
| S-EPMC3477195 | biostudies-other
Project description:This study examined spatial release from masking (SRM) when a target talker was masked by competing talkers or by other types of sounds. The focus was on the role of interaural time differences (ITDs) and time-varying interaural level differences (ILDs) under conditions varying in the strength of informational masking (IM). In the first experiment, a target talker was masked by two other talkers that were either colocated with the target or were symmetrically spatially separated from the target with the stimuli presented through loudspeakers. The sounds were filtered into different frequency regions to restrict the available interaural cues. The largest SRM occurred for the broadband condition followed by a low-pass condition. However, even the highest frequency bandpass-filtered condition (3-6 kHz) yielded a significant SRM. In the second experiment the stimuli were presented via earphones. The listeners identified the speech of a target talker masked by one or two other talkers or noises when the maskers were colocated with the target or were perceptually separated by ITDs. The results revealed a complex pattern of masking in which the factors affecting performance in colocated and spatially separated conditions are to a large degree independent.
| S-EPMC2981113 | biostudies-other
Project description:Research on asynchronous audiovisual speech perception manipulates experimental conditions to observe their effects on synchrony judgments. Probabilistic models establish a link between the sensory and decisional processes underlying such judgments and the observed data, via interpretable parameters that allow testing hypotheses and making inferences about how experimental manipulations affect such processes. Two models of this type have recently been proposed, one based on independent channels and the other using a Bayesian approach. Both models are fitted here to a common data set, with a subsequent analysis of the interpretation they provide about how experimental manipulations affected the processes underlying perceived synchrony. The data consist of synchrony judgments as a function of audiovisual offset in a speech stimulus, under four within-subjects manipulations of the quality of the visual component. The Bayesian model could not accommodate asymmetric data, was rejected by goodness-of-fit statistics for 8/16 observers, and was found to be nonidentifiable, which renders uninterpretable parameter estimates. The independent-channels model captured asymmetric data, was rejected for only 1/16 observers, and identified how sensory and decisional processes mediating asynchronous audiovisual speech perception are affected by manipulations that only alter the quality of the visual component of the speech signal.
| S-EPMC4975115 | biostudies-literature
Project description:People with schizophrenia exhibit impairments in target-speech recognition (TSR) against multiple-talker-induced informational speech masking. Up to date, the underlying neural mechanisms and its relationships with psychotic symptoms remain largely unknown. This study aimed to investigate whether the schizophrenia-associated TSR impairment contribute to certain psychotic symptoms by sharing underlying alternations in cortical gray-matter volume (GMV) with the psychotic symptoms. Participants with schizophrenia (N = 34) and their matched healthy controls (N = 29) were tested for TSR against a two-talker-speech masker. Psychotic symptoms of participants with schizophrenia were evaluated using the Positive and Negative Syndrome Scale. The regional GMV across various cortical regions was assessed using the voxel-based morphometry. The results of partial-correlation and mediation analyses showed that in participants with schizophrenia, the TSR was negatively correlated with the delusion severity, but positively with the GMV in the bilateral superior/middle temporal cortex, bilateral insular, left medial orbital frontal gyrus, left Rolandic operculum, left mid-cingulate cortex, left posterior fusiform, and left cerebellum. Moreover, the association between GMV and delusion was based on the mediating role played by the TSR performance. Thus, in people with schizophrenia, both delusions and the augmented vulnerability of TSR to informational masking are associated with each other and share the underlying cortical GMV reduction, suggesting that the origin of delusion in schizophrenia may be related to disorganized or limited informational processing (e.g., the incapability of adequately filtering information from multiple sources at the perceptual level). The TSR impairment can be a potential marker for predicting delusion severity.
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Project description:PurposeTo study the effects of masked auditory feedback (MAF) on speech fluency in adults with aphasia and/or apraxia of speech (APH/AOS). We hypothesized that adults with AOS would increase speech fluency when speaking with noise. Altered auditory feedback (AAF; i.e., delayed/frequency-shifted feedback) was included as a control condition not expected to improve speech fluency.MethodTen participants with APH/AOS and 10 neurologically healthy (NH) participants were studied under both feedback conditions. To allow examination of individual responses, we used an ABACA design. Effects were examined on syllable rate, disfluency duration, and vocal intensity.ResultsSeven of 10 APH/AOS participants increased fluency with masking by increasing rate, decreasing disfluency duration, or both. In contrast, none of the NH participants increased speaking rate with MAF. In the AAF condition, only 1 APH/AOS participant increased fluency. Four APH/AOS participants and 8 NH participants slowed their rate with AAF.ConclusionsSpeaking with MAF appears to increase fluency in a subset of individuals with APH/AOS, indicating that overreliance on auditory feedback monitoring may contribute to their disorder presentation. The distinction between responders and nonresponders was not linked to AOS diagnosis, so additional work is needed to develop hypotheses for candidacy and underlying control mechanisms.
| S-EPMC4987030 | biostudies-literature
Project description:How speech is separated perceptually from other speech remains poorly understood. Recent research indicates that the ability of an extraneous formant to impair intelligibility depends on the variation of its frequency contour. This study explored the effects of manipulating the depth and pattern of that variation. Three formants (F1+F2+F3) constituting synthetic analogues of natural sentences were distributed across the 2 ears, together with a competitor for F2 (F2C) that listeners must reject to optimize recognition (left = F1+F2C; right = F2+F3). The frequency contours of F1 - F3 were each scaled to 50% of their natural depth, with little effect on intelligibility. Competitors were created either by inverting the frequency contour of F2 about its geometric mean (a plausibly speech-like pattern) or using a regular and arbitrary frequency contour (triangle wave, not plausibly speech-like) matched to the average rate and depth of variation for the inverted F2C. Adding a competitor typically reduced intelligibility; this reduction depended on the depth of F2C variation, being greatest for 100%-depth, intermediate for 50%-depth, and least for 0%-depth (constant) F2Cs. This suggests that competitor impact depends on overall depth of frequency variation, not depth relative to that for the target formants. The absence of tuning (i.e., no minimum in intelligibility for the 50% case) suggests that the ability to reject an extraneous formant does not depend on similarity in the depth of formant-frequency variation. Furthermore, triangle-wave competitors were as effective as their more speech-like counterparts, suggesting that the selection of formants from the ensemble also does not depend on speech-specific constraints.
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