Speech Enhancement—A Review of Modern Methods

A review of techniques to improve distorted speech is presented, noting the strengths and weaknesses of common methods. Speech signals are discussed from the point of view of which features should be preserved to retain both naturalness and intelligibility. Enhancement methods range from classical spectral subtraction and Wiener filtering to recent deep neural network approaches. The difficulty of finding objective acoustic measures that approximate perceptual speech quality is discussed. Suggestions to improve these methods are made.