Masking Properties Research Articles

Perceptual improvement of Wiener filtering employing a post-filter

A major drawback of many speech enhancement methods in speech applications is the generation of an annoying residual noise with musical character. Although the Wiener filter introduces less musical noise than spectral subtraction methods, such noise, however, exists and is perceptually annoying to the listener. A potential solution to this artifact is the incorporation of a psychoacoustic model in the suppression filter design. In this paper a frequency domain optimal linear estimator with perceptual post-filtering is proposed, which incorporates the masking properties of the human hearing system to render the residual noise distortion inaudible. Proposed post-processing presents a modified way to measure the tonality coefficient and relative threshold offset for an optimal estimation of the noise masking threshold. The performance of the proposed enhancement algorithm is evaluated by the segmental SNR, Modified Bark Spectral Distortion (MBSD) and Perceptual Evaluation of Speech Quality (PESQ) measures under various noisy environments and yields better results compared to the Wiener filtering based on Ephraim-Malah's decision-directed approach.

Quantization-Based Digital Audio Watermarking in Discrete Fourier Transform Domain

To explore the principle and performances of Q uantization Index Modulation (QIM) watermarking algorithm , the realization schemes of this algorithm in D iscrete Fourier T ransform (DFT) d omain are classified into three types according to the differences of quantizer parameters , and then the illustrative diagrams of these schemes are given, so the properties of transparency, robustness and capacity of each scheme are concluded. The scheme with best distortion-robustness trade-off is found on that basis. The more efficient embedding and extracting formulas of this scheme are given, and the performances are researched by theoretical analysis rather than computer simulation. The conclusions show that the transparency is in proportion to the square of quantization step and small DFT coefficient leads to poor transparency. The robustness to Additive White Gaussian Noise (AWGN) only relates to the quantization step and the algorithm is susceptible to amplitude scale and resampling attacks. The possible capacity is F o /2 bits per second, which can satisfy various watermarking applications. To improve the robustness, an adaptive quantization algorithm based on masking properties of the Human Auditory System (HAS) is proposed at the end of this paper, and the algorithm is evaluated in the analog channel environment and its robustness is proved by the results.

Perceptual Properties Based Signal Subspace Microphone Array Speech Enhancement Algorithm

摘要: 针对麦克风阵列信号子空间语音增强算法的不足, 结合人耳的听觉掩蔽效应, 提出了改进的信号子空间算法. 提出了通过置信度判断来确定噪声子空间维度的方法, 在噪声子空间上, 通过条件概率的方法估计出噪声功率谱. 在此基础上, 结合人耳的听觉掩蔽效应给出了线性滤波器的一种合理估计. 实验结果表明所提的方法相对于传统算法, 更有效地抑制了噪声, 在多项语音质量评价指标上都有明显的改进. 关键词: 语音增强 / 信号子空间 / 麦克风阵列 / 听觉掩蔽效应 / 特征值分解

Watermarking of Free-view Video

With the advances in image based rendering (IBR) in recent years, generation of a realistic arbitrary view of a scene from a number of original views has become cheaper and faster. One of the main applications of this progress has emerged as free-view TV(FTV), where TV-viewers select freely the viewing position and angle via IBR on the transmitted multiview video. Noting that the TV-viewer might record a personal video for this arbitrarily selected view and misuse this content, it is apparent that copyright and copy protection problems also exist and should be solved for FTV. In this paper, we focus on this newly emerged problem by proposing a watermarking method for free-view video. The watermark is embedded into every frame of multiple views by exploiting the spatial masking properties of the human visual system. Assuming that the position and rotation of the virtual camera is known, the proposed method extracts the watermark successfully from an arbitrarily generated virtual image. In order to extend the method for the case of an unknown virtual camera position and rotation, the transformations on the watermark pattern due to image based rendering operations are analyzed. Based upon this analysis, camera position and homography estimation methods are proposed for the virtual camera. The encouraging simulation results promise not only a novel method, but also a new direction for watermarking research.

High-Efficiency Soft-Error-Tolerant Digital Signal Processing Using Fine-Grain Subword-Detection Processing

The soft error problem in digital circuits is becoming increasingly important as the IC fabrication technology progresses from the deep submicrometer scale to the nanometer scale. This paper proposes a subword-detection processing (SDP) technique and a fine-grain soft-error-tolerance (FGSET) architecture to improve the performance of the digital signal processing circuit. In the SDP technique, the logic masking property of the soft error in the combinational circuit is utilized to mask the single-event upset (SEU) caused by disturbing particles in the inactive area. To further improve the performance, the masked portion of the datapath can be used as the estimation redundancy in the algorithmic softerror-tolerance (ASET) technique. This technique is called subword-detection and redundant processing (SDRP). In the FGSET architecture, the soft error in each processing element (fine grain) can be recovered by the arithmetic datapath-level ASET technique. Analysis of the fast Fourier transform processor example shows that the proposed FGSET architecture can improve the performance of the coarse-grain SET (CGSET) by 8.5 dB. The low-cost SDP technique (1.03x) yields a noise reduction of 5.3 dB over the CGSET approach (1.40x), while the efficient SDRP I (1.57x) and SDRP II (1.88x) techniques outperform the CGSET approach by 24.5 and 30.5 dB, respectively.

Comparative study of ion-exchange resin Indion 204 and Indion 214 for the taste masking of metoclopramide hydrochloride and formulation of rapid-disintegrating tablets

The purpose of this research was to mask the intensely bitter taste of metoclopramide hydrochloride and to formulate a rapid-disintegrating tablet of the taste-masked drug.Taste masking was done by complexing the drug with ion exchange resin, Indion 204 and Indion 214, in different ratios. The complex loading process was optimized for the concentration of resin, swelling time, stirring time, pH, and temperature for maximum drug loading. Drug–resin complexes (DRC) were tested for flow properties, drug content, in-vitro release in simulated salivary fluid, and in simulated gastric fluid (SGF), taste evaluation by the panel method. Taste evaluation of DRC revealed considerable taste masking with the degree of bitterness below threshold value (40 μg/ml) in 0 to 5 min. Complex of both Indion 204 and Indion 214 masked the taste, but on the basis of the comparative study, resin 214 was selected for taste masking property. Disintegrant croscarmellose (5% wt/wt) gave the minimum disintegration time in comparison to crosspovidone and sodium starch glycolate. The batch of tablet containing Pearlitol SD and Avicel (PH102) in the ratio 60:40 and 5% (wt/wt) Croscarmellose showed faster disintegration i.e. 32 s, as compare to marketed tablet. It also revealed rapid drug release (t80, 6 min) in SGF compared with marketed formulation (t80, 9 min).

A Lifting Wavelet Domain Audio Watermarking Algorithm Based on the Statistical Characteristics of Sub-Band Coefficients

In this paper, a new lifting wavelet domain audio watermarking algorithm based on the statistical characteristics of sub-band coefficients is proposed. First of all, an original audio signal was segmented and each segment was divided into two sections. Then, the Barker code was used for synchronization, the LWT (lifting wavelet transform) was performed on each section, a synchronization code and a watermark were embedded into the first section and the second section, respectively, by modifying the statistical average value of the sub-band coefficients. The embed strength was determined adaptively according to the auditory masking property. Experiments show that the embedded watermark has better robustness against common signal processing attacks than present algorithms based on LWT and can resist random cropping in particular.

Audio steganography algorithm based on lifting wavelet transform and matrix coding

With the main purpose of improving the embedding capacity and concealment,using Human Auditory System (HAS) masking properties,an audio steganography algorithm based on lifting wavelet transform and matrix coding to embed secret information was proposed. MPEG Ⅰ audio psychoacoustic model 1 was used to control embedding frames,middle and low frequency coefficients of lifting wavelet transform was choosen to host audio signal,and matrix coding which could improve embedding efficiency and decrease modified proportion was exploited to realize the secret information hiding. The simulation experimental results show that the algorithm not only has excellent concealment and embedding capacity,but also good robustness against noise addition,low pass filtering,resampling,MP3 compression and synchronization attack. Meanwhile,the method can realize blind extraction.

Perceptual speech enhancement exploiting temporal masking properties of human auditory system

The use of simultaneous masking in speech enhancement has shown promise for a range of noise types. In this paper, a new speech enhancement algorithm based on a short-term temporal masking threshold to noise ratio (MNR) is presented. A novel functional model for forward masking based on three parameters is incorporated into a speech enhancement framework based on speech boosting. The performance of the speech enhancement algorithm using the proposed forward masking model was compared with seven other speech enhancement methods over 12 different noise types and four SNRs. Objective evaluation using PESQ revealed that using the proposed forward masking model, the speech enhancement algorithm outperforms the other algorithms by 6–20% depending on the SNR. Moreover, subjective evaluation using 16 listeners confirmed the objective test results.

Distributed Video Coding Based on the Human Visual System

This letter proposes a distributed video coding (DVC) scheme based on the human visual system (HVS). As we know, HVS can seldom sense any changes below the just-noticeable-difference (JND) distortion threshold due to its underlying sensitivity and masking property. Therefore, the un-noticeable signal differences between the original frame and side information need not to be corrected in DVC. Experimental results demonstrate that the proposed algorithm can save the bits-rates significantly without degrading the subjective quality of the reconstructed frames.

Quantifying masking effects of seismic survey reverberation off the Alaskan North Slope.

Quantifying the potential impacts of anthropogenic acoustic noise on marine life faces tremendous hurdles, including defining appropriate metrics to be extracted from the raw acoustic data. In shallow Arctic environments, reverberation from seismic arrays can persist over periods longer than the duration of the direct signal, suggesting that reverberation might play a role in masking communication between endemic animals like the bowhead whale (Balaena mysticetus). Presented here is a quantitative metric related to the masking properties of impulsive anthropogenic signals in shallow water environments. The approach taken is to measure the minimum level of the acoustic noise field, where the level is typically defined in terms of rms pressure or sound exposure. Three time scales need to be defined in order to specify the minimum level: the biologically-relevant energy-integration timescale of a species’s hearing mechanism, the time-scale over which the noise signal can be considered wide-sense stationary, and the time-scale over which significant secular changes take place in the source, receiver, or propagation characteristics of a cyclical (multi-pulse) scenario. Examples of this metric are provided using data collected in 2008 from seismic surveys in the Beaufort Sea in 25–50-m depth water. [Work supported by Shell Exploration and Production Company.]

A 3D-RBS study of irradiation-induced deformation and masking properties of ordered colloidal nanoparticulate masks

The 500 keV Xe 2+ irradiation-induced anisotropic deformation of ordered colloidal silica nanoparticulate masks is followed using 2 MeV 4He + Rutherford Backscattering Spectrometry (RBS) with different measurement geometries and the improved data analysis capabilities of the RBS-MAST spectrum simulation code. The three-dimensional (3D) geometrical transformation from spherical to oblate ellipsoidal and polygonal shape and the decrease of the mask’s hole size is described. The masking properties of the silica monolayer and the depth distribution of Xe in the underlying Si substrate vs. the irradiated Xe 2+ fluence are discussed. Field Emission Scanning Electron Microscopy (FESEM) is applied as complementary characterization tool. Our results give contribution to clarify the impact of ion–nanoparticle interactions on the potentials and limits of nanosphere lithography. We also show the capability of the conventional RBS technique to characterize laterally ordered submicron-sized three-dimensional structures.

A gain factor adapted by masking property and SNR variation for speech enhancement in colored-noise corruptions

A gain factor adapted by both the intra-frame masking properties of the human auditory system and the inter-frame SNR variation is proposed to enhance a speech signal corrupted by additive noise. In this article we employ an averaging factor, varying with time–frequency, to improve the estimate of the a priori SNR. In turn, this SNR estimate is utilized to adapt a gain factor for speech enhancement. This gain factor reduces the spectral variation over successive frames, so the effect of musical residual noise is mitigated. In addition, the simultaneous masking property of the human ears is also employed to adapt the gain factor. Imperceptive residual noise with energy below the noise masking threshold is retained, resulting in a reduction of speech distortion. Experimental results show that the proposed scheme can efficiently reduce the effect of musical residual noise.

Speech enhancement based on speech-presence probability and auditory masking property

In low Signal to Noise Ratio(SNR) environment,the trade-off among the amount of noise reduction,the level of musical residual noise and the speech distortion was the key problem of spectral subtraction speech enhancement.An improved speech enhancement algorithm for low SNR was developed in order to decrease the interference of noise on pure speech.This algorithm was based on the traditional spectral subtraction,and the subtraction parameter was self-adaptively adjusted in the light of the masking properties of human auditory.The speech-presence probability was integrated to estimate the signal and noise,which would avoid the inaccuracy of utilizing Voice Activity Detection(VAD),and increase the robustness.The experimental results demonstrate that this algorithm is effective to reduce the residual noise and the background noise,but not to distort the speech articulation compared to other modified spectral subtraction algorithms,especially for the low SNR noisy speech signal and that being degraded by non-stationary noise.

Performance Analysis of Data Hiding in MPEG-4 AAC Audio

A high capacity data hiding technique was developed for compressed digital audio. As perceptual audio coding has become the accepted technology for storage and transmission of audio signals, compressed audio information hiding enables robust, imperceptible transmission of data within audio signals, thus allowing valuable information to be attached to the content, such as the song title, lyrics, composer's name, and artist or property rights related data. This paper describes simultaneous low bitrate encoding and information hiding for highly compressed audio signals. The information hiding is implemented in the quantization process of the audio content which improves robustness, signal quality, and security. The imperceptibility of the embedded data is ensured based on the masking property of the human auditory system (HAS). The robustness and security are evaluated by various attacking algorithms. Tests with an extended MPEG4 advanced audio coding (AAC) encoder confirm that the method is robust to the regular and singular groups method (RS) and sample pair analysis (SPA) attacks as well as other statistical steganalysis method attacks.

Indinavir-loaded pH-sensitive microparticles for taste masking: toward extemporaneous pediatric anti-HIV/AIDS liquid formulations with improved patient compliance.

The aim of this work was to develop indinavir pediatric anti-HIV/AIDS formulations enabling convenient dose adjustment, ease of oral administration, and improved organoleptic properties by means of the generation of drug-loaded microparticles made of a polymer that is insoluble under intake conditions and dissolves fast in the stomach in order to completely release the active agent. Indinavir-loaded microparticles made of a pH-dependent polymeric excipient soluble at pH < 5, Eudragit E100, were prepared using a double emulsion solvent diffusion technique and the in vitro release profiles characterized. Finally, taste masking properties were evaluated in blind randomized sensory experiments by ten healthy human volunteers. The use of a w/o/o emulsion system resulted in indinavir loads around 90%. Thermal analysis of the microparticles by differential scanning calorimetry revealed that indinavir appeared mainly dispersed at the molecular level. Concentrations of residual organic solvents as determined by gas chromatography were below the upper limits specified by the European Pharmacopeia for pharmaceutical oral formulations. Then, the behavior of drug-containing microparticles in aqueous media at different pH values was assessed. While they selectively dissolved in gastric-like medium, in tap water (intake conditions), the matrix remained almost unchanged and efficiently prevented drug dissolution. Finally, sensoring taste tests performed by volunteers indicated that systems with indinavir loads approximately 15% displayed acceptable taste. This work explored the production of indinavir-containing microparticles based on a common pharmaceutical excipient as a means for the improvement of medicines of drugs involved in the treatment of HIV/AIDS. For systems containing about 15% drug, taste studies confirmed the acceptability of the formulation. In pediatric regimes, this composition would require an acceptable amount of formulation (0.7-1.5 g).

A Subtractive-Type Speech Enhancement Using the Perceptual Frequency-Weighting Function

The present paper describes quality enhancement of speech corrupted by an additive background noise in a single-channel system. The proposed approach is based on the introduction of a perceptual criterion using a frequency-weighting filter in a subtractive-type enhancement process. Although this subtractive-type method is very attractive because of its simplicity, it produces an unnatural and unpleasant residual noise. Thus, it is difficult to select fixed optimized parameters for all speech and noise conditions. A new and effective algorithm is thus developed based on the masking properties of the human ear. This newly developed algorithm allows for an automatic adaptation in the time and frequency of the enhancement system and determines a suitable noise estimate according to the frequency of the noisy input speech. Experimental results demonstrate that the proposed approach can efficiently remove additive noise related to various kinds of noise corruption.

Auditory-Based Spectral Amplitude Estimators for Speech Enhancement

We propose a new family of Bayesian estimators for speech enhancement where the cost function includes both a power law and a weighting factor. The parameters of the cost function, and therefore of the corresponding estimator gain, are chosen based on characteristics of the human auditory system, namely, the compressive nonlinearities of the cochlea, the perceived loudness and the ear's masking properties. It is found that choosing the parameters in this way results in a decrease of the estimator gain at high frequencies. This frequency dependence of the gain improves the noise reduction while limiting the speech distortion. Experimental results show that the new estimators achieve better enhancement performance than existing Bayesian estimators such as those based on the minimum mean-square error (MMSE) of the short-time spectral amplitude (STSA), the MMSE of the logarithm of the STSA (LSA) or the weighted euclidien (WE) error, both in terms of objective and subjective measures.

Masking Property Based Residual Acoustic Echo Cancellation for Hands-Free Communication in Automobile Environment

A residual acoustic echo cancellation method that employs the masking property is proposed to enhance the speech quality of hands-free communication devices in an automobile environment. The conventional masking property is employed for speech enhancement using the masking threshold of the desired clean speech signal. In this Letter, either the near-end speech or residual noise is selected as the desired signal according to the double-talk detector. Then, the residual echo signal is masked by the desired signal (masker). Experiments confirm the effectiveness of the proposed method by deriving the echo return loss enhancement and by examining speech waveforms and spectrograms.

Perceptually Guided Polygon Reduction

The properties of the human visual system are taken into account, along with the geometric aspects of an object, in a new surface remeshing algorithm and a new mesh simplification algorithm. Both algorithms have a preprocessing step and are followed by the remeshing or mesh simplification steps. The preprocessing step computes an importance map that indicates the visual masking potential of the visual patterns on the surface. The importance map is then used to guide the remeshing or mesh simplification algorithms. Two different methods are proposed for computing an importance map that indicates the masking potential of the visual patterns on the surface. The first one is based on the Sarnoff visual discrimination metric, and the second one is inspired by the visual masking tool available in the current JPEG2000 standard. Given an importance map, the surface remeshing algorithm automatically distributes few samples to surface regions with strong visual masking properties due to surface texturing, lighting variations, bump mapping, surface reflectance and inter-reflections. Similarly, the mesh simplification algorithm simplifies more aggressively where the light field of an object can hide more geometric artifacts.