AudioEchoFilter.delay  

// Set the delay on the chorus filter to the max working value.

@script RequireComponent(AudioSource)
@script RequireComponent(AudioEchoFilter)

function Start() {
    GetComponent(AudioEchoFilter).delay = 5000;
}

using UnityEngine;
using System.Collections;

[RequireComponent(typeof(AudioSource))]
[RequireComponent(typeof(AudioEchoFilter))]
public class example : MonoBehaviour {
    void Start() {
        GetComponent<AudioEchoFilter>().delay = 5000;
    }
}

import UnityEngine
import System.Collections

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

    def Start():
        GetComponent[of AudioEchoFilter]().delay = 5000