Adaptive filtering changes filter coefficients over time in response to signals.

Evidence

In adaptive filtering (Haykin, 1989, 2005; Widrow and Stearns, 1985), the goal is that a signal processing function using digital filters can adapt to properties of the input signal in a meaningful way. Technically, adaptation means that the transfer function of the filter is controlled by changing the filter coefficients. Thus, the filter is no longer time-invariant. — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 441

Categorization

• DEFINE: Clear technical definition of what ‘adaptation’ means in the filtering context.
• corroborated: 2 independent passages support this claim — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 441