// 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(AudioSource)]
[RequireComponent(AudioLowPassFilter)]
class example(MonoBehaviour):

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