Search results for "masking"
showing 10 items of 103 documents
Analysis of visually guided eye movements in subjects after whiplash injury
2011
Abstract Objective The aims of present research were to analyze the visually guided eye movements of subjects suffering from the consequences of whiplash injury and the possibility to differentiate patients from feigning subject. We analyzed the role of video-nystagmography for clinical and forensic aspects. Methods It was a prospective case–control study. Detailed history was taken and patients were thoroughly investigated. Smooth pursuit and saccadic eye movements were assessed in 33 patients affected by imbalance following a whiplash injury. A control group of 20 subjects was also evaluated. All tests were executed in neutral neck position and after left and right trunk rotation. Results…
Effect of luminance on photopic visual acuity in the presence of laser speckle
1988
Visual acuity in coherent and incoherent light has been determined by using square-wave gratings of 100% contrast. Luminance was varied from 3 to 400 cd/m2. Coherent illumination resulted in a 40% loss of visual acuity. This is probably due to the masking effect of coherent spatial noise (speckle). However, the most interesting finding is the change in shape of the photopic visual-acuity-luminance function. With coherent illumination, the function is vertically displaced and of a different gradient. An increase in luminance produces a decrease in visual acuity. This indicates that the masking effect of the speckle is dependent on luminance. Two observers were used, and similar results were …
Synergy and masking in odor mixtures: an electrophysiological study of orthonasal vs. retronasal perception
2008
Perceptual interactions in a model of wine woody–fruity binary mixtures were previously reported in a psychophysical study performed through orthonasal stimulation only. However, recent studies suggested that the perception of food-like and nonfood-like odors may depend on the route of stimulation. The aim of the present study was two-fold: first to examine the neural correlates of perceptual interactions using electroencephalogram (EEG)-derived event-related potentials (ERPs) and second to test the influence of the stimulation route on quality perception. Therefore, we designed an experiment with 30 subjects to study perceptual interactions in woody–fruity mixtures and compared ortho- vs. …
The mid-difference hump in forward-masked intensity discrimination
2008
Forward-masked intensity-difference limens (DLs) for pure-tone standards presented at low, medium, and high levels were obtained for a wide range of masker-standard level differences. At a standard level of 25 dB SPL, the masker had a significant effect on intensity resolution, and the data showed a mid-difference hump: The DL elevation was greater at intermediate than at large masker-standard level differences. These results support the hypothesis that the effect of a forward masker on intensity resolution is modulated by the similarity between the masker and the standard. For a given masker-standard level difference, the effect of the masker on the DL was larger for a 55-dB SPL than for t…
Binaural release from masking in forward-masked intensity discrimination: Evidence for effects of selective attention
2012
In a forward-masked intensity discrimination task, we manipulated the perceived lateralization of the masker via variation of the interaural time difference (ITD). The maskers and targets were 500 Hz pure tones with a duration of 30 ms. Standards of 30 and 60 dB SPL were combined with 60 or 90 dB SPL maskers. As expected, the presentation of a forward masker perceived as lateralized to the other side of the head as the target resulted in a significantly smaller elevation of the intensity difference limen than a masker lateralized ipsilaterally. This binaural release from masking in forward-masked intensity discrimination cannot be explained by peripheral mechanisms because varying the ITD l…
Sequential grouping modulates the effect of non-simultaneous masking on auditory intensity resolution.
2012
The presence of non-simultaneous maskers can result in strong impairment in auditory intensity resolution relative to a condition without maskers, and causes a complex pattern of effects that is difficult to explain on the basis of peripheral processing. We suggest that the failure of selective attention to the target tones is a useful framework for understanding these effects. Two experiments tested the hypothesis that the sequential grouping of the targets and the maskers into separate auditory objects facilitates selective attention and therefore reduces the masker-induced impairment in intensity resolution. In Experiment 1, a condition favoring the processing of the maskers and the targ…
Factors limiting performance in a multitone intensity-discrimination task: disentangling non-optimal decision weights and increased internal noise.
2013
To identify factors limiting performance in multitone intensity discrimination, we presented sequences of five pure tones alternating in level between loud (85 dB SPL) and soft (30, 55, or 80 dB SPL). In the "overall-intensity task", listeners detected a level increment on all of the five tones. In the "masking task", the level increment was imposed only on the soft tones, rendering the soft tones targets and loud tones task-irrelevant maskers. Decision weights quantifying the importance of the five tone levels for the decision were estimated using methods of molecular psychophysics. Compatible with previous studies, listeners placed higher weights on the loud tones than on the soft tones i…
Electrophysiological signatures of masked transposition priming in a same-different task: Evidence with strings of letters vs. pseudoletters
2012
Research on masked transposed-letter priming (i.e., jugde-JUDGE triggers a faster response than jupte-JUDGE) has become a key phenomenon to reveal how the brain encodes letter position. Recent behavioural evidence suggests that the mechanism responsible for position coding in a masked priming procedure works with familiar "object" identities (e.g., letters, digits, symbols) but not with unfamiliar object identities (e.g., pseudoletters). Here we used event-related potentials (ERPs) to explore the time course of masked transposition priming of letters vs. pseudoletters in a cue-target same-different matching task. Target stimuli were preceded by a masked prime that could be: (i) identical to…
Factors Influencing Tinnitus Loudness and Annoyance
2006
Objective To evaluate the 2 major components of tinnitus severity, loudness and annoyance, and their degree of dependence on characteristics of tinnitus manifestation, history, and etiology. Design Cross-sectional survey performed during the first months of 2004. Setting Nonclinical population. Participants A total of 4995 members of the German Tinnitus League. Main Outcome Measures Comprehensive screening questionnaire, including the Klockhoff and Lindblom loudness grading system and the miniversion of the Tinnitus Questionnaire. Results A moderate correlation of 0.45 was found between tinnitus loudness and annoyance. Both factors were generally higher in men, those older than 50 years, th…
Does sound stimulation have additive effects on cognitive-behavioral treatment of chronic tinnitus?
2003
Psychological and physiological habituation are major goals in the treatment of patients suffering from chronic tinnitus. This study evaluates whether sound stimulation provided by use of low level white noise generators (NG) enhances the effects of cognitive-behavioral treatment (CBT). 124 outpatients with tinnitus of >6 months received manualized group treatment and were randomly assigned to the NG/no NG conditions. Those with moderate tinnitus-related distress obtained four sessions focusing on education, while severely distressed subjects were treated according to a full 10-session CBT program. Outcome was assessed at post-treatment and at 6- and 18-month follow-up. No additive effects …