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A Continuous-time Speech Enhancement Front-end for Microphone Inputs
Yoo, Heejong; Ellis, Rich; Anderson, David V.; Hasler, Paul; Graham, David W.; Hans, Mat
Keyword(s): noise suppression; speech enhancement; analog VLSI; low-power
Abstract: In this paper, we present a real-time noise suppression system implemented with analog VLSI. The algorithm implemented is designed to reduce stationary background noise in single-microphone signals while preserving the non-stationary signal component. Because the system relies on analog computation rather than digital, it has benefits such as extremely low power consumption and real-time computation. The algorithm is based on an adaptive Wiener filter algorithm, adapted to take advantage of analog processing capabilities provided by floating-gate analog VLSI circuits. Noise suppression processing is performed on continuous-time signals in one-third octave subbands. The analog components described as parts of this system include a C^4 second-order section band-pass filter, peak and minimum detectors, a translinear division circuit, and a differential multiplier. Floating-gate circuits are used to set bias points and adjust offsets.
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