The rolloff rate of a filter is typically expressed in what unit?

The rolloff rate of a filter is typically expressed in decibels per octave (dB/octave) or in orders, which indicates how quickly the filter attenuates unwanted frequencies as they move away from the cutoff frequency.

In the context of filters, the rolloff rate describes the slope of the filter's frequency response—specifically, how many decibels a signal is attenuated per octave of frequency increase. For example, a first-order filter has a rolloff rate of 6 dB/octave, while a second-order filter has a rolloff rate of 12 dB/octave. This measurement provides crucial information for audio engineers and sound designers, as it helps them understand how well the filter will isolate or suppress certain frequencies in an audio signal.

Therefore, expressing the rolloff rate in dB/octave or orders effectively communicates the performance characteristics of the filter in terms of frequency response, making it the standard unit for expressing this specific aspect of filter design.