Noise and Digital Signal Processing
Electronic systems in the context of audio communication perform transmission, recording, playback, analysis, or synthesis of speech signals. Different types of noise and distortion can be characterized, and a number of signal processing concepts exist that can assist in mitigating their effect, thus enhancing the quality or intelligibility of the speech signal. Digital signal processing (DSP) offers a number of powerful tools that, depending on the circumstances, may or may not be applicable to specific types of noise corruptions. The chapter provides a simple and generally intuitive overview of the DSP fundamentals upon which noise reduction methods can be based. Examples are provided that give additional insight into the working and application of the techniques discussed. The chapter also provides an overview of the different stages in a general digital speech communication system and their exposure to, and inherent production of, noise. To characterize noise, some background of stochastic signals and their quantities are reviewed.