Simple audio script glitch

Hello,

I made this script i'll explain what it does when you press down wsad it plays the audio file of grass walking when i release it stopped well it works only for the w key on release the asd keeping looping the audio file is there something i'm doing wrong?

 using UnityEngine;
 using System.Collections;
 
 public class PlayerAudio : MonoBehaviour {
     
     public AudioSource Audio;
     public AudioClip WalkingOnGrass;
 
     // Update is called once per frame
     void Update () {
         if(Input.GetKeyDown("w") || Input.GetKeyDown("s") || Input.GetKeyDown("a") || Input.GetKeyDown("d"))
             audio.Play();
         else if 
         (Input.GetKeyUp("w") || Input.GetKeyDown("s") || Input.GetKeyDown("a") || Input.GetKeyDown("d"))
             audio.Stop(); 
     }
 
 }