• Journal of Broadcast Engineering
• /
• v.8 no.1
• /
• pp.11-18
• /
• 2003

In this paper, we introduce a novel signal quality enhancement algorithm with a perceptual interference analysis and perceptual convolutional noise suppression. A perceptual convolutional noise is reflected in the audible disturbance that can still be recognized after the additional noise suppression and tonality change which is caused by the noise energy excitation. The enhancement system is organized with a perceptual additional noise suppression part and a perceptual convolutional noise suppression part. Experimental results show that these two parts have an equivalent quality enhancement performance.

• Electronics and Telecommunications Trends
• /
• v.33 no.3
• /
• pp.11-21
• /
• 2018

Assessment technologies regarding the perceptual quality of images and videos have been receiving significant attention, as they serve as essential tools for monitoring and improving the quality of various media services. In this paper, we review the technology trends of recent studies on the perceptual quality assessment of images and videos, and discuss the future direction of this research field.

• Speech Sciences
• /
• v.6
• /
• pp.163-179
• /
• 1999

For the set up, management and repair of a mobile communication system, continuous estimation of speech quality is required. Speech quality measurement can be conducted by listener's judgement in a subjective test such as MOS (Mean Opinion Score) test. However, this method is laborious, expensive and time-consuming, it is advisable to predict subjective speech quality via objective measures. This paper presents a robust objective speech quality measure, PLP-CMS (Perceptual Linear Predictive-Cepstral Mean Subtraction), which can predict subjective speech quality in mobile communication systems. PLP-CMS has a high correlation with subjective quality owing to PLP (Perceptual Linear Predictive) analysis and shows a robust performance not being influenced by PSTN (Public Switched Telephone Network) channel effects due to CMS (Cepstral Mean Subtraction). To prove the performance of our proposed algorithm, we carried out subjective and objective quality estimation on speech samples which are variously distorted in a real mobile communication system. As a result, we demonstrated that PLP-CMS has a higher correlation with subjective quality than PSQM (Perceptual Speech Quality Measure) and PLP-CD (Perceptual Linear Predictive-Cepstral Distance).

• Journal of Korea Multimedia Society
• /
• v.22 no.8
• /
• pp.860-873
• /
• 2019

LCD backlight boosting and the integration of boosting and dimming are proposed based on image analysis to maximize perceptual image qualities and to reduce display system power. Based on the histogram of the image data, methods for selecting an image suitable for boosting and for adjusting the optimum backlight brightness are proposed. A comprehensive combined optimization method of LCD backlight boosting, dimming and bypass based on image characteristics is also described. Perceptual image quality enhancement and power consumption are evaluated based on well known image databases. Average subjective image quality is improved by 24.8%, RMS contrast is improved more than 20%, and average power consumption is reduced by 15.94% compared to conventional uniform boosting.

• Journal of Broadcast Engineering
• /
• v.19 no.4
• /
• pp.468-477
• /
• 2014

This paper proposes a novel perceptual quality-based (PQ-based) video coding method with foveated contrast sensitivity (FCS). Conventional methods on PQ-based video coding with FCS achieve minimum loss on perceptual quality of compressed video by exploiting the property of human visual system (HVS), that is, its sensitivity differs by the spatial frequency of visual stimuli. On the other hand, PQ-based video coding with foveated masking (FM) exploits the difference of the sensitivity of the HVS between the central vision and the peripheral vision. In this study, a novel FCS model is proposed which considers both the conventional DCT-based JND model and the FM model. Psychological study is conducted to construct the proposed FCS model, and the proposed model is applied to PQ-based video coding algorithm implemented on HM10.0 reference software. Experimental results show that the proposed method decreases bitrate by the average of 10% without loss on the perceptual quality.

• Phonetics and Speech Sciences
• /
• v.1 no.4
• /
• pp.165-170
• /
• 2009

This study was to investigate for comparison between single rating and average ratings from multiple presentations of the same stimulus for measuring the voice quality of dysphonia using 7-point equal-appearing interval (EAI) rating scale. Overall severity of voice quality for 46 /a/ vowel stimuli (23 stimuli from dysphonia, 23 stimuli from control) was rated by 3 experienced speech-language pathologists (averaged 19 years; range = 7 to 40 years). For average ratings, each stimulus was rated five times in random order and averaged from two to five times. Although higher inter-rater reliability was found in average ratings than in single rating, there were no significant differences in rating scores between single and multiple average ratings judged by experienced listeners, suggesting that auditory perceptual ratings judged by well-trained listeners have relatively good agreement with the same stimulus across the judgment. Larger variations in perceptual ratings were observed for moderate voices than for mild or severe voices, even in the average ratings.

• Speech Sciences
• /
• v.8 no.2
• /
• pp.181-191
• /
• 2001

The acoustic quality of a vowel is known to be mostly determined by the frequencies of the first formant(Fl) and the second formant(F2). The perceptual(or psychological) dimensions of vowel perception were examined in this study. Also the relationships among perceptual dimensions, acoustical dimensions(Fl & F2), and articulatory gestures of vowel were discussed. Using multi-dimensional scaling(MDS) technique, the experiment was performed in order to identify the perceptual dimensions of the perception of Korean vowel. In the experiment 8 Seoul standard speakers performed the similarity rating task of 10 synthesized Korean vowels. Two-dimensional MDS solution based. on the similarity rating scores was obtained. The results showed that two perceptual dimensions, D1 and D2 were correlated strongly with F2 and F1(r = -.895 and .878 respectively), and were so interpreted as 'vowel advancement' and 'vowel height' respectively. The relationship between the perceptual dimensions of vowel and the articulatory positions of tongue suggested that perception may be directly linked to production. Further research problems were discussed in the .final section.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2003.11a
• /
• pp.177-182
• /
• 2003

This study is directed toward determining the number and characteristics of psychologically meaningful perceptual dimensions required for assessing the sound Ouaiity with respect to vehicle interior and/or exterior noises. and toward identifying the acoustical or psychoacoustical bases underlying the perception. By nonmetric MDS and clustring analysis of sound quality data sets on our own, of critical importance are two perceptual dimensions for which subjective verdicts can be interpreted as loudness and sharpness. The perceptual dimensions based upon similarity judgments could be accounted for 48% and 24% of the variance. each of which might be a match for the acoustic parameter "A-weighted maximum pressure level"(r= .85) and for the psychoacoustic parameter "sharpness" (r= .65), respectively. On the other hand, the perceptual dimensions based upon preference ratings could explain 66% and 10% of the variance. where the acoustic parameter "A-weighted maximum pressure leve"(r= .92) might be taken to be a best predictor, but sharpness appeared to be less suitable for the description of Preference behavior. Linked to the results, the problems of quantitative modelling of subjective sound quality evaluation and also of implementing corresponding cognitive combination rule for technical and industrial applications, say having "winner-sound qualify" according to preference criteria will be shortly in discussion.

• The Journal of the Acoustical Society of Korea
• /
• v.29 no.4
• /
• pp.270-277
• /
• 2010

In this paper, we proposed an algorithm that improves tone quality of noisy audio signals by using ICA(Independent Component Analysis) algorithm and perceptual filters. Many algorithms have been proposed to eliminate the noise from the audio signals, such as spectral subtraction method, perceptual filter, etc. The perceptual filter uses a noise that is acquired from silent ranges in the input signal. In this case, the improvement rate of tone quality decreases if the noise energy is changed by the environmental variation in a signal frame. But the proposed method estimates a noise that is changed at each frame using ICA algorithm. The estimated noise is applied to perceptual filter. To show the performance of the proposed algorithm, several tests are performed to various input signals. With the proposed algorithm, we could confirm the enhancement of tone quality in terms of segmental SNR (SSNR), noise-to-mask ratio (NMR) and Degradation Category Rating (DCR) test.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.36 no.11C
• /
• pp.655-661
• /
• 2011

The transmission issues for the scalable video coding extension of H.264/AVC (H.264 SVC) video has been widely studied. In this paper, we propose an objective video-quality assessment metric based on no-reference for H.264 SVC using scalability information. The proposed metric estimate the perceptual video-quality reflecting error conditions with the consideration of the motion vectors, error propagation patterns with the hierarchical prediction structure, quantization parameters, and number of frame which damaged by packet loss. The proposed metric reflects the human perceptual quality of video and we evaluate the performance of proposed metric by using correlation relationship between differential mean opinion score (DMOS) as a subjective quality and proposed one.