Mel Filter Bank
A set of overlapping filters that pools spectral energy into Mel-spaced bands approximating the nonuniform frequency resolution of human hearing.
Rather than treating every FFT bin independently, a Mel filter bank combines neighboring frequencies with triangular or similar weights and produces band energies. The representation retains finer resolution at lower frequencies and compresses the higher-frequency axis.
In MFCC pipelines, log filter-bank energies are the stage before the DCT; in systems such as Whisper, a log-Mel spectrogram can become the model input directly. See MFCC speech feature extraction and Whisper architecture.