// Sets the rolloff of the audio source attached to
    // this script to custom.
    @script RequireComponent(AudioSource)
    function Start() {
        audio.rolloffMode = AudioRolloffMode.Custom;
    }

using UnityEngine;
using System.Collections;

[RequireComponent(typeof(AudioSource))]
public class example : MonoBehaviour {
    void Start() {
        audio.rolloffMode = AudioRolloffMode.Custom;
    }
}

import UnityEngine
import System.Collections

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

    def Start():
        audio.rolloffMode = AudioRolloffMode.Custom