Subjective Test Results Research Articles

Optimal liquid crystal display backlight dimming based on clustered contrast loss

We propose an image adaptive backlight dimming method that quantitatively measures the perceived image quality degradation in terms of brightness and contrast. Unlike conventional methods, the proposed adaptive dimming considers the spatial distribution characteristics of the clipped pixels via a new measure, clusterization, to effectively estimate the perceived contrast loss and prevent the clipping artifact (light saturation). The proposed adaptive dimming achieves an average 17.71% power reduction while keeping the image quality difference to a tolerably low amount, as shown by the subjective mean opinion score test results. Comparing the optimal backlight levels estimated by the proposed method with results from other methods, the proposed backlight dimming is closer to the ground truth backlight levels that are favored by human subjects.

Generalized maximum a posteriori spectral amplitude estimation for speech enhancement

Spectral restoration methods for speech enhancement aim to remove noise components in noisy speech signals by using a gain function in the spectral domain. How to design the gain function is one of the most important parts for obtaining enhanced speech with good quality. In most studies, the gain function is designed by optimizing a criterion based on some assumptions of the noise and speech distributions, such as minimum mean square error (MMSE), maximum likelihood (ML), and maximum a posteriori (MAP) criteria. The MAP criterion shows advantage in obtaining a more reliable gain function by incorporating a suitable prior density. However, it has a problem as several studies showed: although MAP based estimator effectively reduces noise components when the signal-to-noise ratio (SNR) is low, it brings large speech distortion when the SNR is high. For solving this problem, we have proposed a generalized maximum a posteriori spectral amplitude (GMAPA) algorithm in designing a gain function for speech enhancement. The proposed GMAPA algorithm dynamically specifies the weight of prior density of speech spectra according to the SNR of the testing speech signals to calculate the optimal gain function. When the SNR is high, GMAPA adopts a small weight to prevent overcompensations that may result in speech distortions. On the other hand, when the SNR is low, GMAPA uses a large weight to avoid disturbance of the restoration caused by measurement noises. In our previous study, it has been proven that the weight of the prior density plays a crucial role to the GMAPA performance, and the weight is determined based on the SNR in an utterance-level. In this paper, we propose to compute the weight with the consideration of time–frequency correlations that result in a more accurate estimation of the gain function. Experiments were carried out to evaluate the proposed algorithm on both objective tests and subjective tests. The experimental results obtained from objective tests indicate that GMAPA is promising compared to several well-known algorithms at both high and low SNRs. The results of subjective listening tests indicate that GMAPA provides significantly higher sound quality than other speech enhancement algorithms.

Speech enhancement based on Bayesian decision and spectral amplitude estimation

In this paper, a single-channel speech enhancement method based on Bayesian decision and spectral amplitude estimation is proposed, in which the speech detection module and spectral amplitude estimation module are included, and the two modules are strongly coupled. First, under the decisions of speech presence and speech absence, the optimal speech amplitude estimators are obtained by minimizing a combined Bayesian risk function, respectively. Second, using the obtained spectral amplitude estimators, the optimal speech detector is achieved by further minimizing the combined Bayesian risk function. Finally, according to the detection results of speech detector, the optimal decision rule is made and the optimal spectral amplitude estimator is chosen for enhancing noisy speech. Furthermore, by considering both detection and estimation errors, we propose a combined cost function which incorporates two general weighted distortion measures for the speech presence and speech absence of the spectral amplitudes, respectively. The cost parameters in the cost function are employed to balance the speech distortion and residual noise caused by missed detection and false alarm, respectively. In addition, we propose two adaptive calculation methods for the perceptual weighted order p and the spectral amplitude order β concerned in the proposed cost function, respectively. The objective and subjective test results indicate that the proposed method can achieve a more significant segmental signal-noise ratio (SNR) improvement, a lower log-spectral distortion, and a better speech quality than the reference methods.

The Effects of Additional 8-Week Quickness Exercise Applied to Trained Wrestlers in the Category of Cadet, Young and Adults on Agility and Reaction Times

This study was carried out to examine the effects of an additional 8-week quickness exercise applied to trained wrestlers in the category of cadet, young and adults, on their agility and reaction times. When the data results were analyzed, it was observed that there was a significant difference between the agility test results of cadet and young athlete subjects (p 0.05). In conclusion, the results of this study showed that the 8- week quickness exercise applied to trained wrestlers had a positive effect on the agility performance of cadet and young athletes. There was no effect in the category of adult athletes who wrestle in the category of adults in terms of their agility and reaction times.

Improving listeners' experience for movie playback through enhancing dialogue clarity in soundtracks

This paper presents a method for improving users' quality of experience through processing of movie soundtracks. The dialogue clarity enhancement algorithms were introduced for detecting dialogue in movie soundtrack mixes and then for amplifying the dialogue components. The front channel signals (left, right, center) are analyzed in the frequency domain. The selected partials in the center channel signal, which yield high disparity between left and right channels, are detected as dialogue. Subsequently, the dialogue frequency components are boosted to achieve an increased dialogue intelligibility. Techniques for reduction of artifacts in the processed signal are also introduced. It is done through smoothing in the time domain and in the frequency domain, applied to reduce unpleasant artifacts. The results of objective and subjective tests are provided, which prove that an increased dialogue intelligibility is achieved with the aid of the proposed algorithm. The algorithm is particularly applicable in mobile devices while listening in changing conditions and in the presence of noise.

Skin prick test results of atopic asthmatic subjects in a chest disease clinic in Sanliurfa

Objective: Skin prick test (SPT) is used widely to determine the allergens in atopic patients. In this study, we aimed to determine the spectrum of aeroallergen sensitivity of atopic asthmatic subjects in Sanliurfa district. Methods: We evaluated clinical, demographic findings and SPT results of 95 male and 162 female in a total 257 patients who had asthma and allergic symptoms. Results: Most common allergens causing a sensitivity reaction detected in our clinic were as follows; cockroach (56.8%), wheat pollen (53.3%), corn pollen (47.4%), grass pollen (36.5%), poplar tree pollen (26%), house dust mite (19.4%), pepper (16.7%) and cat dander (15.1%). Conclusion: High levels of sensitivity to wheat and corn pollens and relatively low sensitivity levels of cat dander results meet our expectations in the area of agricultural land and where pet ownership is not common. Key words: Atopy, aeroallergens, skin prick test

Auditory Distance Rendering Based on ICPD Control for Stereophonic 3D Audio System

In this letter, we propose a new auditory distance rendering (ADR) algorithm based on the interchannel phase difference (ICPD) control. In the conventional ICPD control, distance perception of the sound image is nonlinearly controlled, and directional localization of the sound image can be biased by changes of the interaural cues. These problems are caused by applying the frequency-independent ICPD without considering the acoustic transfer paths of the system setup. To solve these problems, first, the interaural cues of ear signals are analyzed by binaural auditory simulations. Then, stereophonic ADR filters are designed that produce ear signals with a linearly controlled interaural cross-correlation (IACC) and a consistent interaural level difference (IALD) for sophisticated distance perception under the given stereo setup. Subjective test results show that the proposed algorithm can provide better distance controllability than the conventional method with reduced lateralization blur of the sound image.

The Research of Video Quality Evaluating Based on MATLAB

Video quality impairments mainly caused by noisy transmit channel. No-Reference evaluating method is an important way to predict the video quality due to without any other loader to the transmit channel. Aiming at improve the accuracy and effectiveness of No-Reference video quality evaluating model, a novel variable-weight evaluating model is proposed. Motion intensity is introduced to qualify the variation of video content. And a weight control function is obtained based on the statistic studying method. Then the weight of clearness and smoothness can be adjusted in real time through the weight control function. The variable-weight evaluating model takes into the human perceptual properties. The experimental results show that the variable-weight evaluation model outperforms the existing evaluation models and achieves high correlation with the subjective test results.

Simulation of Occupant Response in Space Capsule Landing Configurations With Suit Hardware

The purpose of this study was to compare the response of the total human model for safety (THUMS) human body finite element model (FEM) to experimental postmortem human subject (PMHS) test results and evaluate possible injuries caused by suit ring elements. Experimental testing evaluated the PMHS response in frontal, rear, side, falling, and spinal impacts. The THUMS was seated in a rigid seat that mirrored the sled buck used in the experimental testing. The model was then fitted with experimental combinations of neck, shoulder, humerus and thigh rings with a five-point restraint system. Experimental seat acceleration data was used as the input for the simulations. The simulation results were analyzed and compared to PMHS measurements to evaluate the response of the THUMS in these loading conditions. The metrics selected to compare the THUMS simulation to PMHS tests were the chest acceleration, seat acceleration and belt forces with additional metrics implemented in THUMS. The chest acceleration of the simulations and the experimental data was closely matched except in the Z-axis (superior/inferior) loading scenarios based on signal analysis. The belt force data of the model better correlated to the experimental results in loading scenarios where the THUMS interacted primarily with the restraint system compared to load cases where the primary interaction was between the seat and the occupant (rear, spinal and lateral impacts). The simulation output demonstrated low injury metric values for the occupant in these loading conditions. In the experimental testing, rib fractures were recorded for the frontal and left lateral impact scenarios. Fractures were not seen in the simulations, most likely due to variations between the simulation and the PMHS initial configuration. The placement of the rings on the THUMS was optimal with symmetric placement about the centerline of the model. The experimental placement of the rings had more experimental variation. Even with this discrepancy, the THUMS can still be considered a valuable predictive tool for occupant injury because it can compare results across many simulations. The THUMS also has the ability to assess a wider variety of other injury information, compared to anthropomorphic test devices (ATDs), that can be used to compare simulation results.

Olfactory dysfunction in children with Kallmann syndrome: relation of smell tests with brain magnetic resonance imaging.

Kallmann syndrome (KS) is a genetic disorder with the distinctive features of hyposmia or anosmia and hypogonadotropic hypogonadism. Though hyposmia/anosmia can be evaluated by both objective and subjective smell tests, there is no study comparing these two methods in KS. The aim of the present case series was to discuss the results of objective and subjective smell tests and compare them to volumetric magnetic resonance imaging (MRI). A total of six adolescent males (aged between 14-18 years) with KS were examined by objective and subjective olfactometry to test smell function and by specific MRI sequences to measure the olfactory bulbs. The objective smell test showed anosmia in all six of the patients. However, the subjective test revealed anosmia in five patients and hyposmia in one patient. Brain MRI showed olfactory bulb aplasia in all six cases. MRI provides robust evaluation of the olfactory bulb volume. Our data show excellent compatibility between the results obtained via objective olfactometry and those obtained by measuring olfactory bulb volume as determined by MRI and therefore demonstrate that objective olfactometry remains a highly reliable test. Furthermore, although the number of subjects studied was small, these data also suggest that cheaper and more easily available subjective tests could be used in preference to the more expensive as well as labor-intensive and time-consuming objective smell tests. In the event of doubts as to the validity of the subjective tests, the objective olfactometry tests can confirm the diagnosis. The bulb volumetric MRI may be also used in difficult cases.

“Ambient Fail” exception messages during breath testing of suspected impaired drivers using the Intoxilyzer® 5000C: a 10-year retrospective analysis

A retrospective analysis of the incidence of the “Ambient Failed” exception message (AFM) generated by the Intoxilyzer® 5000C was conducted during breath testing of suspected impaired drivers over a 10-year period. The incidence of an AFM occurred in only 2.5% (n = 531) of the 21,016 drivers that were tested. Breath tests containing two AFMs (n = 21; approx. 0.1%) were even less frequent. There was no main effect in the incidence of AFMs attributable either to year (p = 0.83), location of testing (p = 0.72), or to use of different instruments (p = 0.59). Additionally, there was no evidence of alcohol, or other interfering substances, in the ambient conditions that may have falsely elevated either the calibration checks or the subject breath test results. The occurrence of an AFM was associated with elevated blood alcohol concentrations (BACs) compared with BACs from test records that did not contain an AFM. The mean (± standard deviation) BAC from breath test records that contained at least one AFM and from those that did not was 208 mg/100 mL (± 68) and 150 mg/100 mL (± 54), respectively. Ambient conditions needed to generate an AFM during breath testing are transient in nature and the triggering of an AFM is more likely to occur in subjects with elevated BACs.

A cost-effective and real-time QoE evaluation method for multimedia streaming services

Traditionally, subjective tests are conducted to obtain the Mean Opinion Score (MOS) or Quality of Experience (QoE) of a video streaming service. However, subjective tests are time-consuming and rather costly. Thus, a cost-effective and real-time QoE evaluation method for video streaming services is presented in this paper. The proposed scheme first adopts subjective tests to find the relationships between the QoE and individual QoS parameters. Next, based on subjective test results, the corresponding QoS---QoE mapping functions for individual QoS metrics are derived using the regression approach. Finally, the integrated QoE function, which is a multi-variate function of multiple QoS metrics, for assessing the overall QoE of video streaming services is proposed. Hence, network/service providers only need to measure related objective QoS parameters while the corresponding MOS/QoE can be easily derived in real time based on the integrated QoE function. Since subjective tests only need to be conducted occasionally for updating the parameters in the QoS---QoE mapping functions, the cost of QoE assessment decreases significantly.

User Quality of Experience of Mulsemedia Applications

User Quality of Experience (QoE) is of fundamental importance in multimedia applications and has been extensively studied for decades. However, user QoE in the context of the emerging multiple-sensorial media (mulsemedia) services, which involve different media components than the traditional multimedia applications, have not been comprehensively studied. This article presents the results of subjective tests which have investigated user perception of mulsemedia content. In particular, the impact of intensity of certain mulsemedia components including haptic and airflow on user-perceived experience are studied. Results demonstrate that by making use of mulsemedia the overall user enjoyment levels increased by up to 77%.

Modeling the heat transfer in a PCM cooling vest

Cooling garments containing phase change materials (PCM) is one of practical techniques used for improving thermal comfort and worker’s performance in hot environments. The efficiency of these garments and their ability in cooling the body has been the subject of much research. In this study, it has been attempted to investigate the way in which heat is transferred from the body to the cooling garment and examine its resulting effect on one’s comfort. So, the three-part system of body–garment–environment has been simulated through the finite element method, and the problem of heat exchange between these three parts has been solved with the help of thermal analysis of ANSYS software. The results of modeling indicated that absorbing body’s excessive heat through PCMs could decrease skin’s temperature to at least 2.6°C. The average of heat absorption by phase change bags was 215.4 W/m2 at the beginning of the process and 128.7 W/m2 within one hour. The accuracy of the model was also verified with the results of subjective tests, and a good agreement between the experimental and model results was shown.

Amputee Subject Testing Protocol, Results, and Analysis of a Powered Transtibial Prosthetic Device.

A powered ankle-foot prothesis and its control system were previously designed and built. To evaluate this prosthesis, amputee subject testing was performed. The testing results are analyzed and compared between the powered prosthesis, passive prosthesis, and able-bodied gait. Qualitative comparison showed the prosthesis achieved the design objectives. During stance phase, active ankle moment was generated in the powered prosthesis before push-off to help the amputee walk more naturally. During swing phase, the powered prosthesis was able to move to natural position to achieve foot clearance. However, the prosthesis is slightly under powered compared with the able-bodied ankle.

Twenty-four-hour ambulatory recording of cerebral hemodynamics, systemic hemodynamics, electrocardiography, and actigraphy during people's daily activities.

The feasibility and utility of wearable 24-h multimodality neuromonitoring during daily activities are demonstrated. We have developed a fourth-generation ambulatory near infrared spectroscopy device, namely NINscan 4. NINscan 4 enables recording of brain function (via cerebral hemodynamics), systemic hemodynamics, electrocardiography, and actigraphy simultaneously and continuously for up to 24 h at 250-Hz sampling rate, during (and with minor restriction to) daily activities. We present initial 24-h human subject test results, with example analysis including (1) comparison of cerebral perfusion and oxygenation changes during wakefulness and sleep over a 24-h period and (2) capturing of hemodynamic changes prior, during and after sudden waken up in the night during sleep. These results demonstrate the first ambulatory 24-h cerebral and systemic hemodynamics monitoring, and its unique advantages including long-term data collection and analysis capability, ability to catch unpredictable transient events during activities of daily living, as well as coregistered multimodality analysis capabilities. These results also demonstrate that NINscan 4's motion artifact at 1-g head movement is smaller than physiological hemodynamic fluctuations during motionless sleep. The broader potential of this technology is also discussed.

Subjective Assessment of Region of Interest-Aware Adaptive Multimedia Streaming Quality

Adaptive multimedia streaming relies on adjusting the video content's bit-rate meet network conditions in the quest to reduce packet loss and resulting video quality degradations. Current multimedia adaptation schemes uniformly adjust the compression over the entire image area. However, research has shown that user attention is focused mostly on certain image areas, denoted areas of maximum user interest (AMUI), and their interest decreases with the increase in distance to the AMUI. The region of interest-based adaptive multimedia streaming scheme (ROIAS) is introduced to perform bit-rate adaptation to network conditions by adjusting video quality relative to the AMUI location. This paper also extends ROIAS to support multiple areas of maximum user interest within the same video frame. This paper presents the performance analysis of ROIAS in terms of the impact on user perceived video quality measured using subjective video quality assessment techniques based on human subjects. The tests use a wide range of video clips, which differ in terms of spatial and temporal complexity and region of interest location and variation. A comparative evaluation of both subjective and objective video quality test results is performed and demonstrate the benefit of using ROIAS for adaptive video quality delivery.

Analysis by synthesis spatial audio coding

This study presents a novel spatial audio coding (SAC) technique, called analysis by synthesis SAC (AbS-SAC), with a capability of minimising signal distortion introduced during the encoding processes. The reverse one-to-two (R-OTT), a module applied in the MPEG Surround to down-mix two channels as a single channel, is first configured as a closed-loop system. This closed-loop module offers a capability to reduce the quantisation errors of the spatial parameters, leading to an improved quality of the synthesised audio signals. Moreover, a sub-optimal AbS optimisation, based on the closed-loop R-OTT module, is proposed. This algorithm addresses a problem of practicality in implementing an optimal AbS optimisation while it is still capable of improving further the quality of the reconstructed audio signals. In terms of algorithm complexity, the proposed sub-optimal algorithm provides scalability. The results of objective and subjective tests are presented. It is shown that significant improvement of the objective performance, when compared to the conventional open-loop approach, is achieved. On the other hand, subjective test show that the proposed technique achieves higher subjective difference grade scores than the tested advanced audio coding multichannel.

Speech enhancement using generalized weighted β-order spectral amplitude estimator

In this paper, a single-channel speech enhancement method based on generalized weighted β-order spectral amplitude estimator is proposed. First, we derive a new kind of generalized weighted β-order Bayesian spectral amplitude estimator, which takes full advantage of both the traditional perceptually weighted estimators and β-order spectral amplitude estimators and can obtain flexible and effective gain function. Second, according to the masking properties of human auditory system, the adaptive estimation methods for the perceptually weighted order p is proposed, which is based on a criterion that inaudible noise may be masked rather than removed. Thereby, the distortion of enhanced speech is reduced. Third, based on the compressive nonlinearity of the cochlea, the spectral amplitude order β can be interpreted as the compression rate of the spectral amplitude, and then the adaptive calculation method of parameter β is proposed. In addition, due to one frame delay, the a priori SNR estimation of decision-directed method in speech activity periods is inaccurate. In order to overcome the drawback, we present a new a priori SNR estimation method by combining predicted estimation with decision-directed rule. The subjective and objective test results indicate that the proposed Bayesian spectral amplitude estimator combined with the proposed a priori SNR estimation method can achieve a more significant segmental SNR improvement, a lower log-spectral distortion and a better speech quality over the reference methods.

A Model for Video Quality Assessment Considering Packet Loss for Broadcast Digital Television Coded in H.264

This paper presents a model to predict video quality perceived by the broadcast digital television (DTV) viewer. We present how noise on DTV can introduce individual transport stream (TS) packet losses at the receiver. The type of these errors is different than the produced on IP networks. Different scenarios of TS packet loss are analyzed, including uniform and burst distributions. The results show that there is a high variability on the perceived quality for a given percentage of packet loss and type of error. This implies that there is practically no correlation between the type of error or the percentage of packets loss and the perceived degradation. A new metric is introduced, theweighted percentageof slice loss, which takes into account the affected slice type in each lost TS packet. We show that this metric is correlated with the video quality degradation. A novel parametric model for video quality estimation is proposed, designed, and verified based on the results of subjective tests in SD and HD. The results were compared to a standard model used in IP transmission scenarios. The proposed model improves Pearson Correlation and root mean square error between the subjective and the predicted MOS.