A Method for Enhancement of the Noisy Hybrid data using Independent Vector Analysis

— This paper presents a method and technique of segregating noisy hybrid data using independent vector analysis (IVA) and minimum mean square error (MMSE) filter technique. Previously, method [1] is presented in which heterogeneous mixture is separated into components using independent vector analysis technique without including any type of noise in it. Similar work is continued with addition of additive white Gaussian noise (AWGN) in heterogeneous mixture (image and sound sources mixture). In proposed approach, IVA is applied to isolate the sources and for de-noising, minimum mean squared error (MMSE) filter is used. IVA is an effective method for segregating mixture of information that is originated from various hybrid sources into its components and it also evades permutation disorder, which usually occurs in independent component analysis (ICA). Previously homogenous sources were mostly mixed and segregated back into components using IVA & ICA techniques while in this paper, heterogeneous sources with the addition of AWGN noise are introduced . The improvement in the results is determined with signal-to-noise ratio (SNR).


A. Blind Source Separation
Signal processing for estimating the actual signals from a mixture of observed signals is a challenging task where there is no adequate information about the sources and mixing environment. Blind source separation (BSS) technique is extensively used in this regard for extracting source signals from mixed speech. BSS leads to applications in many areas for estimation of source signals and images. Brain imaging is a superlative application for BSS. Biomedical engineering applications such as electro encephalogram (EEG) and Magneto encephalography (MEG) are intensively used nowadays to show the signals from muscle activity as well as the desired signal from brain activity. The two signals however can be separated using BSS to achieve the accurate estimation of Brain activity [2]. Other applications covering the communication side include speech improvement for the recognition of noise-robust speech, crosstalk segregation hearing-aid apparatus and Seismic waves Monitoring [3]. BSS generally applied in solving cocktail party scenario [4]. This technique is defined as converging on one auditory speech signal while filtering out the rest of the speech mixture.
Two generally used Blind source algorithms are IVA and ICA. For accurate implementation; both techniques are applied under few assumptions due to the fact that we are unaware regarding mixing atmosphere and source signals. These assumptions include norms that number of mixture signals, must be same or higher than the source signals.

B. Independent Vector Analysis (IVA)
Signal segregation may be performed using ICA algorithm but it faces the limitations of permutation disorder and scaling. Therefore, IVA method is used in the research as it does not face the problem of permutation and IVA technique remains dominant in estimation as it operates in frequency domain. Hence using short time Fourier transform, the signals are initially shifted to frequency domain and after separation of these signals from mixture the estimated signals using Inverse of short time Fourier transform are converted back to time domain. This technique has another advantage of using less memory. IVA model is described in the figure given below. II. PROPOSED METHOD IVA algorithm and minimum mean square error technique is implemented for segregation of noisy heterogeneous sources i.e. mixture of image and sound data. It is prominent that the data of images will be 2-dimensional and that of sound will be 1 dimensional. From literature survey it can be concluded that IVA and ICA had been applied to various homogenous mixtures. However, in the proposed method the implementation of IVA will be done on heterogeneous mixtures assuming that each source in mixture is degraded by Above block diagram explains the methodology of the proposed work. Initially, sound and image sources are taken and noisy mixture is formed. These signals are different in nature as, image is two dimensional and sound is one dimensional. Initially image source is converted to one dimension which is then mixed with sound source. We have two source signals and so we should have at least two mixtures and . Mathematically as: We can rewrite equation as Matrix h is basically mixing matrix ) (5) In expression (5), ○ is element-wise product, while L denotes number of sources and M represents number of mixtures.
AWGN is added to the mixture, where SNR specifies the signal to noise ratio per sample in dB (6) Once this noisy instantaneous mixture is generated out of heterogeneous sources, IVA technique is applied which will segregate our sources but these segregated sources are still noisy because of the addition of AWGN. Therefore, minimum mean square error filtering is used to remove noise and an output of segregated sound and 1-dimensional segregated image is achieved.
For the evaluation, we have opted for SNR, overall as: Where is measured between original sources signal and noisy mixture and is measured between segregated output signals and noisy mixture. Improvement in SNR is depicted by .

III. EXPERIMENTAL RESULTS AND DISCUSSION
Results in the form of are evaluated in this section, after applying IVA technique and MMSE filtering on noisy heterogeneous mixtures. Initially 04 image sources and 04 sound sources are randomly selected.   In table 1, segment wise and overall SNR values are shown.
is the performance evaluation of separated sound source compared to original source and noisy heterogeneous mixture. From data it can be observed that value varies for different mixtures and tests and on average 14dB improvement in signal quality is achieved. In heterogeneous Blind source segregation method [1], overall 15 dB SNR was achieved without incorporating any type of noise. Therefore in the proposed approach, removal of noise from noisy heterogeneous mixture with post-processing MMSE approach was a challenging task.
As compared to the results obtained by [1] without applying MMSE post-processing, our proposed method has shown considerably higher performance. Out of random 50 experiments and tests, 08 results are shown and it can be observed that with the addition of AWGN in the method [1] mixtures, the SNR gain is decreased from average 15 dB values to 1dB. However with incorporation of MMSE postprocessing, the overall SNR gain of the segregated sources is improved.