This slope would continue to extend into very low frequencies, effectively attenuating signal to an indiscernible amplitude. For example, a 12 dB per octave HPF located at 100 Hz would accomplish 12 dB of relative attenuation at 50 Hz, and 24 dB at 25 Hz. The slope of filter attenuation is usually quantified in decibels per octave. A low-pass filter (LPF) attenuates content above a cutoff frequency, allowing lower frequencies to pass through the filter. A high-pass filter (HPF) attenuates content below a cutoff frequency, allowing higher frequencies to pass through the filter. There are two types of pass filters (Fig. An audio pass filter attenuates an entire range of frequencies.
