What kind of digital signal processing audio filter is used to remove unwanted noise from a received SSB signal?

An adaptive filter is a type of digital signal processing (DSP) filter that continuously monitors the incoming signal and automatically alters its own parameters (coefficients) to optimize performance. When receiving an SSB signal, the background noise profile can change rapidly. The adaptive filter detects the periodic nature of human speech and separates it from random, non-periodic background noise. By adjusting itself in real-time, the adaptive filter can effectively "learn" the noise environment and null it out, passing only the desired voice audio. This makes it highly effective for noise reduction (NR) and automatic notch filtering (ANF) in modern transceivers. Crystal-lattice filters are analog hardware components, not DSP audio filters. Hilbert-transform filters are used for generating or processing I/Q signals to create or demodulate SSB, and phase-inverting filters do not inherently remove dynamic background noise.