Abstract— Noise is a random and more accurately a stochastic process. Noise is a vital element in all speech processing systems, which is quite broadband. This means that we will have to narrow down the noise bandwidth so as to receive an input signal noise free or with minimum noise at the output after processing. Presently, Narrow Band Notch filters are being used, which forms its basis upon the second order Gray-Markel lattice structure. These Notch filters are adaptive to track the variations in the characteristics of noise as because noise is random in nature. This system of filters are extensively used as it is merituos based on the fact that the system has very low computational complexity as well as its stable,in response to the random noise.

Abstract—The enormous popularity of the World Wide Web in the early 1990's demonstrated the commercial potential of offering multimedia resources through the digital networks. Since commercial interests seek to use the digital networks to offer digital media for profit, they have a strong interest in protecting their ownership rights. Since the threat of using multimedia information, digital forgeries, and unauthorized sharing (piracy) of digital content have increased among content creators, distributors and users. Today multimedia information piracy alone has subjected all the industries to multi-billion revenue losses. Traditional digital content protection techniques, such as encryption and scrambling, alone cannot provide adequate protection of copyrighted contents, because these technologies are unable to protect digital content once they are decrypted. One way to discourage illegal duplication is to insert information known as watermark, into potentially vulnerable data in such a way that it is impossible to separate the watermark from the data. Digital watermarking is the process of inserting a digital signal or pattern inside a digital image, which provides evidence of authenticity. This paper presents a survey on various information hiding techniques and describes classification of digital Watermarking techniques.