Trigger Sound on Terrain -> Tree Collider

I'm in the process of recreating some old scenes and am adding trees via the terrain editor. Collision is working fine on the trees but I'm running into an issue where I can't trigger anything. Any hit registers as a hit with the terrain instead of the tree.

Is there any way to determine if we've hit a tree so I can trigger the appropriate audio?

 

Random ideas...

Give the trees a tag and in the collision event check the gameObject.tag

Give the trees a different layer using https://docs.unity3d.com/ScriptReference/Terrain-preserveTreePrototypeLayers.html

 

I tried the same thing but unfortunately even with preserving tree prototypes and setting different tags and layers I could not get it to work.

 

OK pretty lazy alternative...

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4.  
5. public class Bump : MonoBehaviour
6. {
7.     [SerializeField] private float tolerance = 0.1f;
8.  
9.     void OnCollisionEnter(Collision collision)
10.     {
11.         if (collision.gameObject.name == "Terrain") {
12.             Vector3 hitLocation = collision.contacts[0].point;
13.             float terrainHeight = Terrain.activeTerrain.SampleHeight(hitLocation);
14.             if (hitLocation.y - tolerance > terrainHeight) Debug.Log("Tree");
15.             else Debug.Log("Ground");
16.         }
17.     }
18. }