# Audio Low Pass Filter

> Reference for the Audio Low Pass filter, which passes low frequencies and removes high frequencies.

The **Audio Low Pass Filter** passes low frequencies of an [AudioSource](/engine/6000.0/manual/audio/reference/class-audio-source.md) or all sound reaching an [AudioListener](/engine/6000.0/manual/audio/reference/class-audio-listener.md) while removing frequencies higher than the **Cutoff Frequency**.

## Properties


**The AudioGroup Inspector displays the configurable properties of an Audio Low Pass Filter.:**
![](/api/media?file=/engine/6000.0/media/images/AudioLowPassFilter.png)

| ***Property:***         | ***Function:***                                                             |
| ----------------------- | --------------------------------------------------------------------------- |
| **Cutoff Frequency**    | Lowpass cutoff frequency in Hertz (range 0.0 to 22000.0, default = 5000.0). |
| **Lowpass Resonance Q** | Lowpass resonance quality value (range 1.0 to 10.0, default = 1.0).         |

## Details

The **Lowpass Resonance Q** (short for Lowpass Resonance Quality Factor) determines how much the filter's self-resonance is dampened. Higher lowpass resonance quality indicates a lower rate of energy loss, that is the oscillations die out more slowly.

The **Audio Low Pass Filter** has a Rolloff curve associated with it, making it possible to set **Cutoff Frequency** over distance between the AudioSource and the AudioListener.

Sounds propagate very differently given the environment. For example, to compliment a visual fog effect add a subtle low-pass to the Audio Listener. The high frequencies of a sound being emitted from behind a door will be filtered out by the door and so won't reach the listener. To simulate this, simply change the Cutoff Frequency when opening the door.