Problems when i have multiple enemies on the same scene C#

This might be a complex one but i have a basic AI script i have written that can "Hear" the player using colliders, the script works fine except when there are multiple enemies at once. When one of them hears the player, they all do. Here is the complete EnemyAI script:

 using UnityEngine;
 using System.Collections;
 
 public class EnemyAi : MonoBehaviour {
 
     Transform target; //the enemy's target
     float moveSpeed = 2; //move speed
     float minDist = 0.9f;
     float maxDistance = 5;
     float rotationSpeed = 3; //speed of turning
     bool canHear = false;
     float attackDistance = 1;
     bool canAttack = true;
     Transform player;
     float hearRange = 20;
     public bool couldHearGun = false;
     
     Transform myTransform; //current transform data of this enemy
 
     // Use this for initialization
     void Start () {
         target = GameObject.FindWithTag("PlayerCenter").transform; //target the player
     }
     void Awake()
     {
         myTransform = transform; //cache transform data for easy access/preformance
     }
     // Update is called once per frame
     void Update () {
         player = GameObject.Find("Player").transform;
         if(Vector3.Distance(transform.position, player.position) <= hearRange && couldHearGun){
             Debug.Log("hear the gun");
             canHear = true;
             StartCoroutine(HearPlayer(10));
         }
 
         GameObject Player = GameObject.Find("Player");
         CharacterControler characterControler = Player.GetComponent<CharacterControler>();
         if(characterControler.couldHear && characterControler.makesSound){
             canHear = true;
         }
         if(canHear){
             StartCoroutine(HearPlayer(10));
         }
         
         //rotate to look at the player
         if(Vector3.Distance(transform.position, target.position) <= maxDistance || canHear){
         myTransform.rotation = Quaternion.Slerp(myTransform.rotation, Quaternion.LookRotation(target.position - myTransform.position), rotationSpeed*Time.deltaTime);
         }
 
         //move towards the player
         if(Vector3.Distance(transform.position, target.position) <= maxDistance || canHear){
             if(Vector3.Distance(transform.position, target.position) >= minDist){ 
         myTransform.position += myTransform.forward * moveSpeed * Time.deltaTime;
         }
         }
         if(Vector3.Distance(transform.position, target.position) <= attackDistance && canAttack){
             characterControler.health -= 0.15f;
             canAttack = false;
             characterControler.health -= 0.15f;
             StartCoroutine(attackCooldown(1));
         }
     }
     public IEnumerator HearPlayer(float delay){
         yield return new WaitForSeconds(delay);
         canHear = false;
     }
     public IEnumerator attackCooldown (float delay){
         yield return new WaitForSeconds(delay);
         canAttack = true;
     }
 }
 

and here is the complete gun script which makes the sound:

 using UnityEngine;
 using System.Collections;
 
 public class PistolRay : MonoBehaviour {
 
     bool canFire = true;
     public GameObject decal;
     public float clipAmmo = 8;
     public float storedAmmo = 80;
     float missingShots = 0;
     GameObject player;
     GameObject characterControler;
     bool reloading = false;
 
     // Use this for initialization
     void Start () {
     }
     
     // Update is called once per frame
     void Update () {
         player = GameObject.Find("Player");
         CharacterControler characterControler = player.GetComponent<CharacterControler>();
         characterControler.ammoCount = clipAmmo;
         characterControler.totalAmmo = storedAmmo;
 
         RaycastHit hit;
         Ray shooterRay = new Ray(transform.position, transform.forward);
 
         if(Input.GetButton("Fire1") && canFire && clipAmmo > 0){
             if(GameObject.Find ("EnemyAi") != null){
                 GameObject enemy = GameObject.Find("EnemyAi");
                 Debug.Log("Test");
             EnemyAi enemyAi = enemy.GetComponent<EnemyAi>();
             enemyAi.couldHearGun = true;
             StartCoroutine (SoundCooldown(1));
             }
         }
 
         if(Input.GetButton("Fire1") && canFire && clipAmmo > 0){
             Debug.DrawRay (transform.position, transform.forward, Color.green);
                 if(Physics.Raycast(shooterRay, out hit, Mathf.Infinity)){
                 if(hit.collider.tag == "Enemy"){
                     hit.transform.GetComponent<EnemyCC>().health -= 15;
                 }
             }
             var hitRotation = Quaternion.FromToRotation(Vector3.up, hit.normal);
             Instantiate(decal, hit.point, hitRotation);    
             //GameObject decalInstance = 
             //decal.transform.parent = hit.transform;
             canFire = false;
             clipAmmo -= 1;
             missingShots += 1;
             StartCoroutine(FireRate(1));
             }
         if(Input.GetButtonDown("Fire1") && canFire && clipAmmo == 0 && !reloading){
             reloading = true;
             StartCoroutine(ReloadTime(3));
         }
 
         if(Input.GetButtonDown("Reload") && storedAmmo != 8 && !reloading){
             reloading = true;
             StartCoroutine(ReloadTime(3));
         }
         }
     public IEnumerator FireRate (float delay){
         yield return new WaitForSeconds(delay);
         canFire = true;
     }
     public IEnumerator SoundCooldown(float delay){
         GameObject enemy = GameObject.Find("EnemyAI");
         EnemyAi enemyAi = enemy.GetComponent<EnemyAi>();
         yield return new WaitForSeconds(delay);
         enemyAi.couldHearGun = false;
 
     }
     public IEnumerator ReloadTime (float delay){
         yield return new WaitForSeconds(delay);
         reloading = false;
         if(storedAmmo >= 8){
             storedAmmo -= missingShots;
             clipAmmo += missingShots;
             missingShots = 0;
         }
     }
 }

there is also a character controller script which does a similar thing but its a long script and very messy but i can post if needed.

thanks for any help