High pass filter


Audio: high pass filter (0:03)

High pass filter
Figure: high pass filter

high pass filter plays high pass filtered white noise using a fixed order filter and varying the cutoff frequency from 100Hz to 10,000Hz. This creates a sound that gets gradually brighter and hissier and simulates the sound of a door opening in a spaceship. The high pass filter figure, the waveform, shows the high pass filtered sound getting quieter and quieter as it loses more and more of its low frequencies.

High pass filtering passes frequencies above a cutoff frequency and reduces the amplitude of frequencies below.

A high pass filter does the opposite of a low pass filter.

High pass filtering does not mimic the behaviour of sound in nature. In real life, natural surfaces absorb high frequency sound and pass low frequency sound, not the other way round. In other words, natural surfaces act as a low pass filter, not a high pass filter.

High pass filtering is used to eliminate unwanted low frequency noise in a sound. High pass filtering does not mimic natural sound and is an excellent technique for producing unusual sweeping and swooshing sound effects that have no real life equivalent.