High pass filter allows high frequencies, to go through , but cuts, or attenuation, of the frequency is below the threshold point.

How loudspeakers use high pass filters

A high pass filter is used in an audio system to pass high frequencies while filtering or cutting low frequencies. The high pass filter is used with small speakers for example, to remove low frequencies. In many cases these filters are built into the loudspeaker, but in some more complex speaker settings you can connect a high-pass filter unit to the system.

How high pass filters work with microphones

Some brands of microphones include a selectable filter. These devices, usually designed to record at a higher level, automatically block sounds below a certain hertz level. These settings are useful when recording in locations such as office buildings or warehouses where the HVAC system keeps the rumble low. These filters capture the signal by eliminating the nose.

It’s better to capture good sound than fix bad sound in post. A microphone with a built-in filter provides better sound quality than a conventional microphone that was algorithmically installed after the recording session ended.

How to Use High Pass Filters in Audio Editing

In tools like Audacity, the high pass filter that is applied to the signal mimics a hardware filter. This attenuates the sound below a given threshold.

Audacity screenshot showing the high pass filter

Specify the frequency in hertz and roll-off in decibels per octave. Audacity then attenuates the relative loudness (dB) of the signal with increasing intensity the lower the signal’s threshold frequency.

Many audio editing environments include similar functionality.

How High Pass Filters Work

The high pass filter (like its cousin, the low pass filter) uses some technique to eliminate or reduce the input signal below a certain threshold. There’s no specific way this works.

Decibel drop plot using a high pass filter

Some filters have a hard cap, effectively suppressing noise below a threshold, while others reduce the signal below a certain point.

Похожие записи