scholarly journals Estimates of Ripple-Density Resolution Based on the Discrimination From Rippled and Nonrippled Reference Signals

2019 ◽  
Vol 23 ◽  
pp. 233121651882443 ◽  
Author(s):  
Dmitry I. Nechaev ◽  
Olga N. Milekhina ◽  
Alexander Ya Supin
Keyword(s):  
Test Stimulus ◽  
Temporal Processing ◽  
Temporal Structure ◽  
Reference Stimulus ◽  
Resolution Limits ◽  
The Mean ◽  
Excitation Pattern ◽  
Ripple Phase ◽  
Pattern Resolution ◽  
Density Resolution

Rippled-spectrum stimuli are used to evaluate the resolution of the spectro-temporal structure of sounds. Measurements of spectrum-pattern resolution imply the discrimination between the test and reference stimuli. Therefore, estimates of rippled-pattern resolution could depend on both the test stimulus and the reference stimulus type. In this study, the ripple-density resolution was measured using combinations of two test stimuli and two reference stimuli. The test stimuli were rippled-spectrum signals with constant phase or rippled-spectrum signals with ripple-phase reversals. The reference stimuli were rippled-spectrum signals with opposite ripple phase to the test or nonrippled signals. The spectra were centered at 2 kHz and had an equivalent rectangular bandwidth of 1 oct and a level of 70 dB sound pressure level. A three-alternative forced-choice procedure was combined with an adaptive procedure. With rippled reference stimuli, the mean ripple-density resolution limits were 8.9 ripples/oct (phase-reversals test stimulus) or 7.7 ripples/oct (constant-phase test stimulus). With nonrippled reference stimuli, the mean resolution limits were 26.1 ripples/oct (phase-reversals test stimulus) or 22.2 ripples/oct (constant-phase test stimulus). Different contributions of excitation-pattern and temporal-processing mechanisms are assumed for measurements with rippled and nonrippled reference stimuli: The excitation-pattern mechanism is more effective for the discrimination of rippled stimuli that differ in their ripple-phase patterns, whereas the temporal-processing mechanism is more effective for the discrimination of rippled and nonrippled stimuli.

scholarly journals High Ripple-Density Resolution for Discriminating Between Rippled and Nonrippled Signals: Effect of Temporal Processing or Combination Products?

2021 ◽  
Vol 25 ◽  
pp. 233121652110101
Author(s):  
Dmitry I. Nechaev ◽  
Olga N. Milekhina ◽  
Marina S. Tomozova ◽  
Alexander Y. Supin
Keyword(s):  
Low Frequency ◽  
Noise Signal ◽  
Density Variation ◽  
Choice Procedure ◽  
Masker Level ◽  
Reference Signals ◽  
Forced Choice Procedure ◽  
The Mean ◽  
Density Resolution

The goal of the study was to investigate the role of combination products in the higher ripple-density resolution estimates obtained by discrimination between a spectrally rippled and a nonrippled noise signal than that obtained by discrimination between two rippled signals. To attain this goal, a noise band was used to mask the frequency band of expected low-frequency combination products. A three-alternative forced-choice procedure with adaptive ripple-density variation was used. The mean background (unmasked) ripple-density resolution was 9.8 ripples/oct for rippled reference signals and 21.8 ripples/oct for nonrippled reference signals. Low-frequency maskers reduced the ripple-density resolution. For masker levels from −10 to 10 dB re. signal, the ripple-density resolution for nonrippled reference signals was approximately twice as high as that for rippled reference signals. At a masker level as high as 20 dB re. signal, the ripple-density resolution decreased in both discrimination tasks. This result leads to the conclusion that low-frequency combination products are not responsible for the task-dependent difference in ripple-density resolution estimates.

scholarly journals The development of auditory temporal processing during the first year of life

2021 ◽  
Author(s):  
Laurianne Cabrera ◽  
Bonnie K. Lau
Keyword(s):  
Temporal Processing ◽  
Temporal Structure ◽  
Temporal Information ◽  
First Year ◽  
Auditory Temporal Processing ◽  
Speech Stimuli ◽  
Temporal Cues ◽  
Neurophysiological Studies ◽  
Psychophysical Studies ◽  
First Year Of Life

The processing of auditory temporal information is important for the extraction of voice pitch, linguistic information, as well as the overall temporal structure of speech. However, many aspects regarding its early development remains not well understood. This paper reviews the development of different aspects of auditory temporal processing during the first year of life when infants are acquiring their native language. First, potential mechanisms of neural immaturity are discussed in the context of neurophysiological studies. Next, what is known about infant auditory capabilities is considered with a focus on psychophysical studies involving non-speech stimuli to investigate the perception of temporal fine structure and envelope cues. This is followed by a review of studies involving speech stimuli, including those that present vocoded signals as a method of degrading the spectro-temporal information available to infant listeners. Finally, we highlight key findings from the cochlear implant literature that illustrate the importance of temporal cues in speech perception.

Combining statistical learning and geostatistical approaches in a spatiotemporal framework for low flow estimation

2021 ◽  
Author(s):  
Johannes Laimighofer ◽  
Michael Melcher ◽  
Juraj Parajka ◽  
Gregor Laaha
Keyword(s):  
Statistical Learning ◽  
Mean Squared Error ◽  
Temporal Structure ◽  
Empirical Orthogonal Functions ◽  
Regression Coefficients ◽  
Low Flow ◽  
Support Vector ◽  
Spatiotemporal Model ◽  
Residual Field ◽  
The Mean

<p><span>This paper aims to develop a spatiotemporal model to estimate monthly low flow quantiles Q95 [P(Q<Q95=0.05)] standardized by catchment area in Austria. Our dataset consists of 325 gauging stations that where consistently monitored between 1976 to 2015, and it covers about 60% of the national territory of Austria. </span></p><p><span>In a first step we are adapting a spatiotemporal model initially designed for modeling air pollution data. This approach is based on empirical orthogonal functions (EOF), that should capture the temporal structure of the spatiotemporal model. The EOFs are weighted by regression coefficients estimated by universal kriging. We extend the model by using GLM-boosting, LASSO, Principal Component Regression (PCR) and Random Forest (RF) for selecting the regression coefficients of the EOFs. Furthermore, we do not limit the kriging structure of the residual field to geographical coordinates but use a broader approach of physiographic kriging. In a second step we implement separate models for the mean parts of the model and the residual parts of the model. The mean field is defined by statistical learning methods as RF, GAM-boosting, LASSO and Support Vector Machines (SVM). For the residual field we define two different approaches, either the </span><span>method developed in the first step</span><span> or spatiotemporal kriging.</span></p><p><span>Model performance is evaluated by cross validation and the best model is selected by the mean squared error (MSE). </span></p><p> </p>

Rippled Depth Thresholds: Estimates Obtained by Discrimination From Rippled and Nonrippled Reference Signals

2019 ◽  
Vol 105 (6) ◽  
pp. 1198-1205
Author(s):  
Alexander Ya. Supin ◽  
Olga N. Milekhina ◽  
Dmitry I. Nechaev
Keyword(s):  
Frequency Analysis ◽  
Temporal Processing ◽  
Complex Spectrum ◽  
Pattern Processing ◽  
Reference Signals ◽  
Excitation Pattern ◽  
Processing Mechanisms ◽  
Processing Mechanism

The objective of the study was to better understand of contribution of excitation-pattern and temporal-processing mechanisms of frequency analysis to discrimination of complex-spectrum signals in various discrimination tasks. Using rippled-spectrum signals, the ripple depth thresholds were measured as functions of ripple density under conditions of rippled or non-rippled reference signals. With rippled reference signals, the ripple depth thresholds were as low as 0.11 at low ripple densities (2–3 cycles/oct) and rose to 1.0 at a ripple density of 8.9 cycles/oct. For non-rippled reference signals, ripple depth thresholds were nearly the same as for rippled reference signals at ripple densities of up to 7 cycles/oct; at ripple densities of 10 cycles/oct and higher, ripple depth thresholds rose slowly and reached 1.0 at a ripple density of 26 cycles/oct. The results hypothetically suggest contributions of the excitation-pattern processing and temporal-processing mechanisms of frequency analysis to discrimination of rippled signals. The excitation-pattern mechanism featured low depth thresholds at low ripple densities but could not function at ripple densities above 10 cycles/oct. The temporal-processing mechanism manifested at higher ripple densities and non-rippled reference stimuli.

scholarly journals Multiple Irrelevant Duration Information Affects the Perception of Relevant Duration Information: Interference With Selective Processing of Duration

i-Perception ◽  
2020 ◽  
Vol 11 (6) ◽  
pp. 204166952097322
Author(s):  
Hitomi Kawahara ◽  
Yuko Yotsumoto
Keyword(s):  
Temporal Processing ◽  
Target Stimulus ◽  
Target Duration ◽  
Visual Environment ◽  
Behavioral Experiments ◽  
Cortical Areas ◽  
Duration Information ◽  
The Mean ◽  
Selective Processing ◽  
Perceived Duration

In the human visual environment, the ability to perceive only relevant duration is important for various activities. However, a relatively small number of studies have investigated how humans process multiple durations, in comparison with the processing of one or two durations. We investigated the effects of multiple irrelevant durations on the perception of relevant duration. In four behavioral experiments, the participants were instructed to pay attention to a target stimulus while ignoring the distractors; then, they reproduced the target duration. We manipulated three aspects of the distractors: number, duration range, and cortical distance to the target. The results showed that the presence of multiple irrelevant durations interfered with the processing of relevant duration in terms of the mean perceived duration and the variability of the perceived duration. The interference was directional; that is, longer (shorter) irrelevant durations made the reproduced durations longer (shorter). Moreover, the interference was not likely to depend on the cortical distance between the target and the distractors, suggesting an involvement of relatively higher cortical areas. These results demonstrate that multiple irrelevant duration information affects the temporal processing of relevant duration information and suggest that multiple independent clocks assigned to each of the durations may not exist.

COLOUR PERCEPTION OF LED POINT LIGHT SOURCES IN SCOTOPIC VISION

2021 ◽  
Author(s):  
Riho Ogawa ◽  
Midori Tanaka ◽  
Takahiko Horiuchi
Keyword(s):  
Test Stimulus ◽  
Blackbody Radiation ◽  
Reference Stimulus ◽  
Light Sources ◽  
Small Field ◽  
Colour Perception ◽  
Scotopic Vision ◽  
Normal Individuals ◽  
Point Light

When stimuli are made sufficiently small, colour-normal individuals report a loss in hue perception, similar to tritanopia. This effect is referred to as small-field tritanopia. The interaction between small-field tritanopia and the rods working in scotopic vision has not been clarified. In this study, the problem is investigated by freely adjusting the hue, lightness, and saturation of the test stimulus to match the colour of the reference stimulus by observers. Three colours on the blackbody radiation trajectory with colour temperatures of 3500K, 5400K, and 11600K were used as reference colours. Each stimulus subtended a diameter of 6' and 10.8'. The 5400K and 11600K stimuli were distributed diagonally from the lower left to the upper right of each reference stimulus in the CIE 1976 u’v’ uniform chromaticity scale diagram. The distribution was similar to those of tritanopia. For the 3500K stimulus, the result did not show the influence of small-field tritanopia.

Background-induced flicker enhancement in cat retinal horizontal cells. II. Spatial properties

1990 ◽  
Vol 64 (2) ◽  
pp. 326-340 ◽  
Author(s):  
R. Nelson ◽  
R. Pflug ◽  
S. M. Baer
Keyword(s):  
Test Stimulus ◽  
Exponential Decay ◽  
Horizontal Cell ◽  
Stimulus Size ◽  
Slit Width ◽  
Horizontal Cells ◽  
Test Region ◽  
Length Constant ◽  
Region Model ◽  
The Mean

1. Intracellular recordings have been made from cat retinal horizontal cells stimulated with flickering test spots. Dim backgrounds increase flicker amplitudes in response to small but not large test stimuli. 2. This background-induced flicker enhancement has been measured for different slit- and square-test stimulus widths and the results compared with two spatial models for the enhancement effect. 3. In the "dark test-region" model it is argued that rods within the test region are unresponsive to background stimuli because of prior saturation by the test stimulus. Background-evoked rod signals decay passively from regions outside the test stimulus through a syncytial network into the recording site, where they act on the cone-to-horizontal-cell synapse, increasing its gain. 4. In the "changing length-constant" model rod signals reduce the length constant of a syncytial network by uncoupling the cells within it. This causes an increased response to small but not large test stimuli. 5. Both models are analytically evaluated with the use of a conductive-sheet approximation to the syncytial network. Expressions are derived for network polarization [(V(0, 0)] as a function of stimulus size. The specific stimulus shapes considered are disks, rectangles, slits, and squares in both bright and dark varieties. From these expressions predictions of response enhancement as a function of stimulus size are made for both models. 6. The dark test-region model provides for an exponential decay of flicker enhancement as a function of slit width but a steeper-than-exponential decay with the width of squares, in close agreement with experimental data. 7. The changing length-constant model makes qualitatively similar predictions. Flicker enhancement declines nearly exponentially with slit width. For square-shaped test stimuli the predicted decline of flicker enhancement with size is somewhat shallower than either the dark test-region-model curve or the experimentally determined curve. 8. As recorded in the same set of cells and under the same set of stimulus conditions (with the use of both slit- and square-test stimuli), the mean length constant of the peak-to-peak flicker component in the horizontal-cell response is 168 +/- 18 (SE) microns with the background and 232 +/- 45 microns in the dark. The mean length constant for the background-induced flicker enhancement, as fit by dark test-region-model curves, is 186 +/- 22 microns (n = 9).(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Stability and spatio-temporal structure in fish assemblages of two floodplain lagoons of the lower Orinoco River

2009 ◽  
Vol 7 (4) ◽  
pp. 719-736 ◽  
Author(s):  
Nirson González ◽  
Carlos Lasso ◽  
Judith Rosales
Keyword(s):  
Aquatic Vegetation ◽  
Fish Assemblages ◽  
Hydrological Cycle ◽  
Temporal Structure ◽  
Biotic Interactions ◽  
High Water ◽  
Water Phase ◽  
Fish Assemblage Structure ◽  
Biological Interactions ◽  
The Mean

Fish assemblage structure and variability were analyzed in two floodplain lagoons (Las Arhuacas and Los Cardonales) along the lower Orinoco over a hydrological cycle. Every three months during continuous three-day sampling, experimental gill nets (5 to 12.5 cm of mesh opening) and 1 mm-mesh seine nets were utilized according to the types of habitats presents. A total of 133 fish species were found in Las Arhuacas and 95 species in Cardonales. Fifty five and 17 species were exclusive to Las Arhuacas and Los Cardonales respectively, and 77 were common to both lagoons. In Las Arhuacas, the most speciesrich orders were Characiformes, Siluriformes, Perciformes and Gymnotiformes and in Los Cardonales, the most species-rich orders were Characiformes, Siluriformes, Clupeiformes and Perciformes. The richness, abundance and biomass were significantly higher (p < 0.001) in Arhuacas than in Cardonales. In general, the fishes assemblage was highly variable during the high water phase and moderately stable during low water phase in both lagoons, with more stability or less variability in Cardonales than Arhuacas. Also, there were significant differences in the fish assemblages between the two lagoons, mainly during low waters (ANOSIM; p < 0.001). The species that contributed most to the mean dissimilarity between the lagoons were Hypostomus argus, Aphanotorulus ammophilus, Potamorhina altamazonica, Prochilodus mariae, Loricaria gr. cataphracta, Oxydoras sifontesi, Hydrolycus armatus, Hyphopthalmus edentatus and Pterodoras rivasi. The last four species were more commonly collected in Los Cardonales. Also, the species of small size (mainly SL < 5 cm) such as Rhinosardinia amazonica, Moenkhausia sp. 1 "lepidura", Moenkhausia sp. 2, Aphyocharax alburnus, Characidium sp. 1, Moenkhausia sp. 3, Exodon paradoxus and Roeboides dientonito contributed to the mean dissimilarity among the beach and aquatic vegetation habitats. The patterns of the species assemblage organization were related to the dynamics of the floods. Non-random (i. e., deterministic) associations between species caused by the selection of habitats and/or to biological interactions, apparently were more common during low waters when there is an increased density of fish and so the biotic interactions are intensified. Stochastic associations, on the other hand, seemed to be more common during high water when species are more dispersed.

Effects of Speech Materials on the Loudness Discomfort Level

1979 ◽  
Vol 44 (4) ◽  
pp. 435-458 ◽  
Author(s):  
Randall C. Beattie ◽  
Bradly J. Edgerton ◽  
David W. Gager
Keyword(s):  
Test Stimulus ◽  
Sound Pressure Level ◽  
Sound Pressure ◽  
Stimulus Presentation ◽  
Pressure Level ◽  
Psychophysical Method ◽  
Speech Stimuli ◽  
Modified Method ◽  
The Mean ◽  
High Degree

Clinicians have used speech stimuli when measuring the loudness discomfort level (LDL) to determine the upper intensity limit for test stimulus presentation, and to select the saturation sound pressure level for an individual’s hearing aid. Because little research has investigated the effects of speech stimuli on the LDL, this study was undertaken to compare LDLs using six commercially available speech materials on 120 normally hearing listeners. Our comparisons showed no significant differences between the mean scores for any of the speech stimuli. These findings suggest that any differences in the mean LDLs among studies probably are not attributable to the speech stimuli. The intrasession reliability of LDL measurement was also assessed using a modified method of limits procedure with 2-dB increments and instructions stressing initial discomfort. It was concluded that examiners probably could attain a high degree of reliability by simply averaging the results of two ascending trials, because 95% of these test/retest differences did not exceed 6 dB. Our findings were integrated with previous studies in terms of: (1) test stimuli; (2) listener experience; (3) instructional set; and (4) psychophysical method. This discussion points to many unanswered questions and concludes that the LDL should be interpreted very cautiously. Moreover, it is suggested that the stimuli selected for LDL measurement should reflect the examiner’s purpose.

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