Lowpass cutoff frequency in hz. 10.0 to 22000.0. Default = 5000.0.

	// Moves the cuttoutFrequency from 10 to 22000 following a Sinus function
	// Attach this to an audio source with a LowPassFilter to listen it working.
	@script RequireComponent(AudioSource)
	@script RequireComponent(AudioLowPassFilter)
	function Update() {
		GetComponent(AudioLowPassFilter).cutoffFrequency = (Mathf.Sin(Time.time)*11010 + 11000);
	}

using UnityEngine;
using System.Collections;

[RequireComponent(typeof(AudioSource))]
[RequireComponent(typeof(AudioLowPassFilter))]
public class Example : MonoBehaviour {
    void Update() {
        GetComponent<AudioLowPassFilter>().cutoffFrequency = Mathf.Sin(Time.time) * 11010 + 11000;
    }
}

import UnityEngine
import System.Collections

[RequireComponent(typeof(AudioSource))]
[RequireComponent(typeof(AudioLowPassFilter))]
public class Example(MonoBehaviour):

	def Update() as void:
		GetComponent[of AudioLowPassFilter]().cutoffFrequency = ((Mathf.Sin(Time.time) * 11010) + 11000)