Highlowpass

Highlowpass is a term used in signal processing to describe a two-band filtering approach that emphasizes the low and high frequency regions while reducing energy in the midrange. It is not a standardized term, and its exact meaning can vary between disciplines, software packages, or designers. In practice, highlowpass usually refers to architectures that combine high-pass and low-pass characteristics in a single block.

One common realization is a parallel arrangement in which a high-pass filter and a low-pass filter receive the same input and their outputs are summed. With appropriate crossover frequencies and filter slopes, the spectrum is shaped to pass the outer bands and attenuate midband content, creating a two-band or hollow-like effect useful for spectral emphasis or creative processing.

An alternative is a cascaded configuration where the signal passes through a high-pass stage and then a low-pass stage (or vice versa). Depending on the cutoffs and slopes, this can yield a band-pass response that selects a middle frequency range, or a broader two-band response when combined with gain adjustments. The implementation choice affects phase, latency, and computational load.

Applications include audio tone shaping, crossovers in loudspeaker systems, and measurement setups that require suppression of mid-frequency energy or noise outside a target band. In digital systems, highlowpass can be realized with IIR or FIR filters, with attention to stability, phase behavior, and real-time constraints.

Because highlowpass is not a universally defined term, readers should consult the specific documentation or design notes of a given tool or paper to understand how the term is used in that context.