how to apply "WaitForSeconds" ? Help Me

Hello how are you? I need help with a problem … as applied “WaitForSecond” in this script?

the idea is that at high RPM, sound the exhaust sound, and have to wait some time to return to play …
I let the script, it works … just repeats each time the sound is just …

SCRIPT (C#) :

using UnityEngine;
using System.Collections;

public class exaustSound : MonoBehaviour {
	
	public AudioClip exaust;
	public float exaustVolume=1f;
	public float exaustpitch=1f;
	
	AudioSource exaustSource;
	[HideInInspector]
	Drivetrain drivetrain;
	
	float volumeFactor;
	int i,k;	
	
	AudioSource CreateAudioSource(AudioClip clip, bool loop, bool playImmediately, Vector3 position) {
		GameObject go = new GameObject("audio");
		go.transform.parent = transform;
		go.transform.localPosition = position;
		go.transform.localRotation = Quaternion.identity;
		go.AddComponent(typeof(AudioSource));
		go.audio.clip = clip;
		go.audio.playOnAwake = false;
		if (loop==true){
			go.audio.volume = 0;
			go.audio.loop = true;
		}
		else 
			go.audio.loop = false;
		
		if (playImmediately) go.audio.Play();
		
		return go.audio;
	}
	
	void Start () {
		
		exaustSource= CreateAudioSource(exaust, false, false,Vector3.zero);
		exaustSource.volume=exaustVolume;
		
	
	}
		
	
	void Update () {
        drivetrain= GetComponent<Drivetrain>();
		if (drivetrain) {		
			if (this.drivetrain.rpm > 10000f) {if (!exaustSource.isPlaying) exaustSource.Play();
			
			
			else exaustSource.Stop();
		}
		
	}
}

A couple simple ways to use a Coroutine in C#:

using UnityEngine;
using System.Collections;
 
public class Example : MonoBehaviour 
{
	int count = 0;
	
	void Awake()
	{
		StartCoroutine(MyCoroutine(3));	
	}
	
	IEnumerator MyCoroutine(int WaitTime)
	{
		yield return new WaitForSeconds(WaitTime);
		print ("Next Coroutine");
		StartCoroutine(MyOtherCoroutine());
	}
	
	IEnumerator MyOtherCoroutine()
	{
		while(true)
		{
			yield return new WaitForSeconds(1);
			count++;
			print (count);
			yield return new WaitForEndOfFrame();	
		}
	}
}