Colonic Pressure Signal Denoising Based on Improved Threshold Function and Threshold Optimization.

Wavelet threshold noise reduction is widely used because of its simple algorithm and small computation. The properties of the threshold function are studied and a new two-parameter adjustable threshold function is designed to solve the problems of signal loss and local oscillations caused by soft and hard threshold function noise reduction. The threshold function has the properties of continuity, small constant deviation and high order differentiability. Meanwhile, an artificial hummingbird algorithm based on a mixture of Cubic chaotic mapping, global Cauchy variation and golden sine strategy is used for optimization of thresholds and adjustment factors. Applying this algorithm in noise reduction of colonic pressure signals, most of the noise can be filtered out and the details of colonic peristaltic signals are preserved.