High pass filters are one of the most important tools in Pro Audio. This equalization tool is used to remove all frequencies below a set point, allowing high frequencies to pass while removing low frequencies. In audio, there are two main types of filters, high-pass, and low-pass filters.
Generally speaking, a high-pass filter is used to remove unneeded frequencies. Every instrument operates within a specific band of frequencies, and using a high-pass filter, the frequencies below that band can be removed. For example, the male speaking voice operates from about 80 Hertz, and a high-pass filter can be used to remove the frequencies below 80 Hertz.
High-pass filters can also be used for removing noise and unnecessary frequencies. Traffic, wind, air-conditioning fans, and more create noise in our audio signal, which can be mostly composed of low-frequency energy. High-pass filters can be used to remove this noise.
Plosives or Pia pops can be another issue in audio. A high-pass filter can be used to mitigate the effect of these pops. While it’s always best to avoid them by separating yourself from the microphone or by using a pop filter, sometimes it’s not possible.
Aside from removing noise and unnecessary frequencies, high-pass filters can also improve the tone of your mix. For example, if a bass guitar and a kick drum are fighting for the same frequency band, you can high-pass one of them to make room for the other.
High-pass filters can also be used in speaker systems to separate the lows and the highs. Crossovers are used to send only low information to the woofer and high-pass filters to send only high information to the tweeter. Filters have two main controls, cutoff frequency, and slope. The cutoff frequency sets where the filter begins, and the slope determines the rate of the filter.
In summary, a high-pass filter is a useful tool in audio that can be used to remove unneeded frequencies, noise, and unnecessary sounds. It can also be used to improve the tone of your mix, and in speaker systems to separate the lows and the highs. With the right use of cutoff frequency and slope, high-pass filters can be an essential tool for any audio professional.