Low Pass Filter

Filters are used to shape noise or other sounds, so that they become louder at some frequencies and softer at others. This gives the sound some added character. A low pass filter leaves low frequencies unaffected, and filters out high frequencies. Low pass filters are used everywhere that you need to smooth out the jitters from noisy real-world data, like the gyroscope or acceleration sensors in satellites, robots, and smartphones. It takes in a cutoff parameter, which controls how strongly it filters out high frequencies.

What happens to the spectrum as you change the cutoff?

Mathematically, a low pass filter can be expressed as output[i] = a * input[i] + (1 - a) * output[i - 1], where a is a number between 0 and 1. This type of low pass filter is sometimes also called a one-zero filter.

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