From ba271b9eac3177da44af6c6627fdd77490680cf5 Mon Sep 17 00:00:00 2001
From: Hyunwook Ha <hyunwookha@gmail.com>
Date: Fri, 20 Jun 2025 09:12:04 +0900
Subject: [PATCH 1/2] Add index++ to 2D Tutorial's AudioController.Update()

---
 .../MonoGameLibrary/Audio/AudioController.cs                  | 4 ++--
 .../MonoGameLibrary/Audio/AudioController.cs                  | 4 ++--
 .../src/17-Scenes/MonoGameLibrary/Audio/AudioController.cs    | 4 ++--
 .../MonoGameLibrary/Audio/AudioController.cs                  | 4 ++--
 .../MonoGameLibrary/Audio/AudioController.cs                  | 4 ++--
 .../MonoGameLibrary/Audio/AudioController.cs                  | 4 ++--
 .../MonoGameLibrary/Audio/AudioController.cs                  | 4 ++--
 .../MonoGameLibrary/Audio/AudioController.cs                  | 4 ++--
 .../MonoGameLibrary/Audio/AudioController.cs                  | 4 ++--
 .../src/24-Shaders/MonoGameLibrary/Audio/AudioController.cs   | 4 ++--
 .../MonoGameLibrary/Audio/AudioController.cs                  | 4 ++--
 .../MonoGameLibrary/Audio/AudioController.cs                  | 4 ++--
 .../27-Conclusion/MonoGameLibrary/Audio/AudioController.cs    | 4 ++--
 13 files changed, 26 insertions(+), 26 deletions(-)

diff --git a/Tutorials/learn-monogame-2d/src/15-Audio-Controller/MonoGameLibrary/Audio/AudioController.cs b/Tutorials/learn-monogame-2d/src/15-Audio-Controller/MonoGameLibrary/Audio/AudioController.cs
index 1bffd636..7126c8d3 100644
--- a/Tutorials/learn-monogame-2d/src/15-Audio-Controller/MonoGameLibrary/Audio/AudioController.cs
+++ b/Tutorials/learn-monogame-2d/src/15-Audio-Controller/MonoGameLibrary/Audio/AudioController.cs
@@ -109,9 +109,9 @@ public void Update()
             if (instance.State == SoundState.Stopped && !instance.IsDisposed)
             {
                 instance.Dispose();
+                _activeSoundEffectInstances.RemoveAt(index);
             }
-
-            _activeSoundEffectInstances.RemoveAt(index);
+            index++;
         }
     }
 
diff --git a/Tutorials/learn-monogame-2d/src/16-Working-With-SpriteFonts/MonoGameLibrary/Audio/AudioController.cs b/Tutorials/learn-monogame-2d/src/16-Working-With-SpriteFonts/MonoGameLibrary/Audio/AudioController.cs
index 1bffd636..7126c8d3 100644
--- a/Tutorials/learn-monogame-2d/src/16-Working-With-SpriteFonts/MonoGameLibrary/Audio/AudioController.cs
+++ b/Tutorials/learn-monogame-2d/src/16-Working-With-SpriteFonts/MonoGameLibrary/Audio/AudioController.cs
@@ -109,9 +109,9 @@ public void Update()
             if (instance.State == SoundState.Stopped && !instance.IsDisposed)
             {
                 instance.Dispose();
+                _activeSoundEffectInstances.RemoveAt(index);
             }
-
-            _activeSoundEffectInstances.RemoveAt(index);
+            index++;
         }
     }
 
diff --git a/Tutorials/learn-monogame-2d/src/17-Scenes/MonoGameLibrary/Audio/AudioController.cs b/Tutorials/learn-monogame-2d/src/17-Scenes/MonoGameLibrary/Audio/AudioController.cs
index 1bffd636..7126c8d3 100644
--- a/Tutorials/learn-monogame-2d/src/17-Scenes/MonoGameLibrary/Audio/AudioController.cs
+++ b/Tutorials/learn-monogame-2d/src/17-Scenes/MonoGameLibrary/Audio/AudioController.cs
@@ -109,9 +109,9 @@ public void Update()
             if (instance.State == SoundState.Stopped && !instance.IsDisposed)
             {
                 instance.Dispose();
+                _activeSoundEffectInstances.RemoveAt(index);
             }
-
-            _activeSoundEffectInstances.RemoveAt(index);
+            index++;
         }
     }
 
diff --git a/Tutorials/learn-monogame-2d/src/18-Texture-Wrapping/MonoGameLibrary/Audio/AudioController.cs b/Tutorials/learn-monogame-2d/src/18-Texture-Wrapping/MonoGameLibrary/Audio/AudioController.cs
index 1bffd636..7126c8d3 100644
--- a/Tutorials/learn-monogame-2d/src/18-Texture-Wrapping/MonoGameLibrary/Audio/AudioController.cs
+++ b/Tutorials/learn-monogame-2d/src/18-Texture-Wrapping/MonoGameLibrary/Audio/AudioController.cs
@@ -109,9 +109,9 @@ public void Update()
             if (instance.State == SoundState.Stopped && !instance.IsDisposed)
             {
                 instance.Dispose();
+                _activeSoundEffectInstances.RemoveAt(index);
             }
-
-            _activeSoundEffectInstances.RemoveAt(index);
+            index++;
         }
     }
 
diff --git a/Tutorials/learn-monogame-2d/src/19-User-Interface-Fundamentals/MonoGameLibrary/Audio/AudioController.cs b/Tutorials/learn-monogame-2d/src/19-User-Interface-Fundamentals/MonoGameLibrary/Audio/AudioController.cs
index 1bffd636..7126c8d3 100644
--- a/Tutorials/learn-monogame-2d/src/19-User-Interface-Fundamentals/MonoGameLibrary/Audio/AudioController.cs
+++ b/Tutorials/learn-monogame-2d/src/19-User-Interface-Fundamentals/MonoGameLibrary/Audio/AudioController.cs
@@ -109,9 +109,9 @@ public void Update()
             if (instance.State == SoundState.Stopped && !instance.IsDisposed)
             {
                 instance.Dispose();
+                _activeSoundEffectInstances.RemoveAt(index);
             }
-
-            _activeSoundEffectInstances.RemoveAt(index);
+            index++;
         }
     }
 
diff --git a/Tutorials/learn-monogame-2d/src/20-Implementing-UI-With-Gum/MonoGameLibrary/Audio/AudioController.cs b/Tutorials/learn-monogame-2d/src/20-Implementing-UI-With-Gum/MonoGameLibrary/Audio/AudioController.cs
index 1bffd636..7126c8d3 100644
--- a/Tutorials/learn-monogame-2d/src/20-Implementing-UI-With-Gum/MonoGameLibrary/Audio/AudioController.cs
+++ b/Tutorials/learn-monogame-2d/src/20-Implementing-UI-With-Gum/MonoGameLibrary/Audio/AudioController.cs
@@ -109,9 +109,9 @@ public void Update()
             if (instance.State == SoundState.Stopped && !instance.IsDisposed)
             {
                 instance.Dispose();
+                _activeSoundEffectInstances.RemoveAt(index);
             }
-
-            _activeSoundEffectInstances.RemoveAt(index);
+            index++;
         }
     }
 
diff --git a/Tutorials/learn-monogame-2d/src/21-Customizing-Gum-UI/MonoGameLibrary/Audio/AudioController.cs b/Tutorials/learn-monogame-2d/src/21-Customizing-Gum-UI/MonoGameLibrary/Audio/AudioController.cs
index 1bffd636..7126c8d3 100644
--- a/Tutorials/learn-monogame-2d/src/21-Customizing-Gum-UI/MonoGameLibrary/Audio/AudioController.cs
+++ b/Tutorials/learn-monogame-2d/src/21-Customizing-Gum-UI/MonoGameLibrary/Audio/AudioController.cs
@@ -109,9 +109,9 @@ public void Update()
             if (instance.State == SoundState.Stopped && !instance.IsDisposed)
             {
                 instance.Dispose();
+                _activeSoundEffectInstances.RemoveAt(index);
             }
-
-            _activeSoundEffectInstances.RemoveAt(index);
+            index++;
         }
     }
 
diff --git a/Tutorials/learn-monogame-2d/src/22-Snake-Game-Mechanics/MonoGameLibrary/Audio/AudioController.cs b/Tutorials/learn-monogame-2d/src/22-Snake-Game-Mechanics/MonoGameLibrary/Audio/AudioController.cs
index 1bffd636..7126c8d3 100644
--- a/Tutorials/learn-monogame-2d/src/22-Snake-Game-Mechanics/MonoGameLibrary/Audio/AudioController.cs
+++ b/Tutorials/learn-monogame-2d/src/22-Snake-Game-Mechanics/MonoGameLibrary/Audio/AudioController.cs
@@ -109,9 +109,9 @@ public void Update()
             if (instance.State == SoundState.Stopped && !instance.IsDisposed)
             {
                 instance.Dispose();
+                _activeSoundEffectInstances.RemoveAt(index);
             }
-
-            _activeSoundEffectInstances.RemoveAt(index);
+            index++;
         }
     }
 
diff --git a/Tutorials/learn-monogame-2d/src/23-Completing-The-Game/MonoGameLibrary/Audio/AudioController.cs b/Tutorials/learn-monogame-2d/src/23-Completing-The-Game/MonoGameLibrary/Audio/AudioController.cs
index 1bffd636..7126c8d3 100644
--- a/Tutorials/learn-monogame-2d/src/23-Completing-The-Game/MonoGameLibrary/Audio/AudioController.cs
+++ b/Tutorials/learn-monogame-2d/src/23-Completing-The-Game/MonoGameLibrary/Audio/AudioController.cs
@@ -109,9 +109,9 @@ public void Update()
             if (instance.State == SoundState.Stopped && !instance.IsDisposed)
             {
                 instance.Dispose();
+                _activeSoundEffectInstances.RemoveAt(index);
             }
-
-            _activeSoundEffectInstances.RemoveAt(index);
+            index++;
         }
     }
 
diff --git a/Tutorials/learn-monogame-2d/src/24-Shaders/MonoGameLibrary/Audio/AudioController.cs b/Tutorials/learn-monogame-2d/src/24-Shaders/MonoGameLibrary/Audio/AudioController.cs
index 1bffd636..7126c8d3 100644
--- a/Tutorials/learn-monogame-2d/src/24-Shaders/MonoGameLibrary/Audio/AudioController.cs
+++ b/Tutorials/learn-monogame-2d/src/24-Shaders/MonoGameLibrary/Audio/AudioController.cs
@@ -109,9 +109,9 @@ public void Update()
             if (instance.State == SoundState.Stopped && !instance.IsDisposed)
             {
                 instance.Dispose();
+                _activeSoundEffectInstances.RemoveAt(index);
             }
-
-            _activeSoundEffectInstances.RemoveAt(index);
+            index++;
         }
     }
 
diff --git a/Tutorials/learn-monogame-2d/src/25-Packaging-Game/MonoGameLibrary/Audio/AudioController.cs b/Tutorials/learn-monogame-2d/src/25-Packaging-Game/MonoGameLibrary/Audio/AudioController.cs
index 1bffd636..7126c8d3 100644
--- a/Tutorials/learn-monogame-2d/src/25-Packaging-Game/MonoGameLibrary/Audio/AudioController.cs
+++ b/Tutorials/learn-monogame-2d/src/25-Packaging-Game/MonoGameLibrary/Audio/AudioController.cs
@@ -109,9 +109,9 @@ public void Update()
             if (instance.State == SoundState.Stopped && !instance.IsDisposed)
             {
                 instance.Dispose();
+                _activeSoundEffectInstances.RemoveAt(index);
             }
-
-            _activeSoundEffectInstances.RemoveAt(index);
+            index++;
         }
     }
 
diff --git a/Tutorials/learn-monogame-2d/src/26-Publish-To-Itch/MonoGameLibrary/Audio/AudioController.cs b/Tutorials/learn-monogame-2d/src/26-Publish-To-Itch/MonoGameLibrary/Audio/AudioController.cs
index 1bffd636..7126c8d3 100644
--- a/Tutorials/learn-monogame-2d/src/26-Publish-To-Itch/MonoGameLibrary/Audio/AudioController.cs
+++ b/Tutorials/learn-monogame-2d/src/26-Publish-To-Itch/MonoGameLibrary/Audio/AudioController.cs
@@ -109,9 +109,9 @@ public void Update()
             if (instance.State == SoundState.Stopped && !instance.IsDisposed)
             {
                 instance.Dispose();
+                _activeSoundEffectInstances.RemoveAt(index);
             }
-
-            _activeSoundEffectInstances.RemoveAt(index);
+            index++;
         }
     }
 
diff --git a/Tutorials/learn-monogame-2d/src/27-Conclusion/MonoGameLibrary/Audio/AudioController.cs b/Tutorials/learn-monogame-2d/src/27-Conclusion/MonoGameLibrary/Audio/AudioController.cs
index 1bffd636..7126c8d3 100644
--- a/Tutorials/learn-monogame-2d/src/27-Conclusion/MonoGameLibrary/Audio/AudioController.cs
+++ b/Tutorials/learn-monogame-2d/src/27-Conclusion/MonoGameLibrary/Audio/AudioController.cs
@@ -109,9 +109,9 @@ public void Update()
             if (instance.State == SoundState.Stopped && !instance.IsDisposed)
             {
                 instance.Dispose();
+                _activeSoundEffectInstances.RemoveAt(index);
             }
-
-            _activeSoundEffectInstances.RemoveAt(index);
+            index++;
         }
     }
 

From 9028deb0529bb529ece12f98ca0390b3c60f9271 Mon Sep 17 00:00:00 2001
From: Hyunwook Ha <hyunwookha@gmail.com>
Date: Wed, 25 Jun 2025 11:50:07 +0900
Subject: [PATCH 2/2] Update Code according to
 https://github.com/MonoGame/docs.monogame.github.io/pull/148

---
 .../MonoGameLibrary/Audio/AudioController.cs   | 16 ++++++++--------
 .../MonoGameLibrary/Audio/AudioController.cs   | 16 ++++++++--------
 .../MonoGameLibrary/Audio/AudioController.cs   | 16 ++++++++--------
 .../MonoGameLibrary/Audio/AudioController.cs   | 16 ++++++++--------
 .../MonoGameLibrary/Audio/AudioController.cs   | 16 ++++++++--------
 .../MonoGameLibrary/Audio/AudioController.cs   | 16 ++++++++--------
 .../MonoGameLibrary/Audio/AudioController.cs   | 16 ++++++++--------
 .../MonoGameLibrary/Audio/AudioController.cs   | 18 +++++++++---------
 .../MonoGameLibrary/Audio/AudioController.cs   | 16 ++++++++--------
 .../MonoGameLibrary/Audio/AudioController.cs   | 16 ++++++++--------
 .../MonoGameLibrary/Audio/AudioController.cs   | 16 ++++++++--------
 .../MonoGameLibrary/Audio/AudioController.cs   | 16 ++++++++--------
 .../MonoGameLibrary/Audio/AudioController.cs   | 16 ++++++++--------
 13 files changed, 105 insertions(+), 105 deletions(-)

diff --git a/Tutorials/learn-monogame-2d/src/15-Audio-Controller/MonoGameLibrary/Audio/AudioController.cs b/Tutorials/learn-monogame-2d/src/15-Audio-Controller/MonoGameLibrary/Audio/AudioController.cs
index 7126c8d3..02a5759b 100644
--- a/Tutorials/learn-monogame-2d/src/15-Audio-Controller/MonoGameLibrary/Audio/AudioController.cs
+++ b/Tutorials/learn-monogame-2d/src/15-Audio-Controller/MonoGameLibrary/Audio/AudioController.cs
@@ -100,18 +100,18 @@ public AudioController()
     /// </summary>
     public void Update()
     {
-        int index = 0;
-
-        while (index < _activeSoundEffectInstances.Count)
+        for (int i = _activeSoundEffectInstances.Count - 1; i >= 0; i--)
         {
-            SoundEffectInstance instance = _activeSoundEffectInstances[index];
+            SoundEffectInstance instance = _activeSoundEffectInstances[i];
 
-            if (instance.State == SoundState.Stopped && !instance.IsDisposed)
+            if (instance.State == SoundState.Stopped)
             {
-                instance.Dispose();
-                _activeSoundEffectInstances.RemoveAt(index);
+                if (!instance.IsDisposed)
+                {
+                    instance.Dispose();
+                }
+                _activeSoundEffectInstances.RemoveAt(i);
             }
-            index++;
         }
     }
 
diff --git a/Tutorials/learn-monogame-2d/src/16-Working-With-SpriteFonts/MonoGameLibrary/Audio/AudioController.cs b/Tutorials/learn-monogame-2d/src/16-Working-With-SpriteFonts/MonoGameLibrary/Audio/AudioController.cs
index 7126c8d3..02a5759b 100644
--- a/Tutorials/learn-monogame-2d/src/16-Working-With-SpriteFonts/MonoGameLibrary/Audio/AudioController.cs
+++ b/Tutorials/learn-monogame-2d/src/16-Working-With-SpriteFonts/MonoGameLibrary/Audio/AudioController.cs
@@ -100,18 +100,18 @@ public AudioController()
     /// </summary>
     public void Update()
     {
-        int index = 0;
-
-        while (index < _activeSoundEffectInstances.Count)
+        for (int i = _activeSoundEffectInstances.Count - 1; i >= 0; i--)
         {
-            SoundEffectInstance instance = _activeSoundEffectInstances[index];
+            SoundEffectInstance instance = _activeSoundEffectInstances[i];
 
-            if (instance.State == SoundState.Stopped && !instance.IsDisposed)
+            if (instance.State == SoundState.Stopped)
             {
-                instance.Dispose();
-                _activeSoundEffectInstances.RemoveAt(index);
+                if (!instance.IsDisposed)
+                {
+                    instance.Dispose();
+                }
+                _activeSoundEffectInstances.RemoveAt(i);
             }
-            index++;
         }
     }
 
diff --git a/Tutorials/learn-monogame-2d/src/17-Scenes/MonoGameLibrary/Audio/AudioController.cs b/Tutorials/learn-monogame-2d/src/17-Scenes/MonoGameLibrary/Audio/AudioController.cs
index 7126c8d3..02a5759b 100644
--- a/Tutorials/learn-monogame-2d/src/17-Scenes/MonoGameLibrary/Audio/AudioController.cs
+++ b/Tutorials/learn-monogame-2d/src/17-Scenes/MonoGameLibrary/Audio/AudioController.cs
@@ -100,18 +100,18 @@ public AudioController()
     /// </summary>
     public void Update()
     {
-        int index = 0;
-
-        while (index < _activeSoundEffectInstances.Count)
+        for (int i = _activeSoundEffectInstances.Count - 1; i >= 0; i--)
         {
-            SoundEffectInstance instance = _activeSoundEffectInstances[index];
+            SoundEffectInstance instance = _activeSoundEffectInstances[i];
 
-            if (instance.State == SoundState.Stopped && !instance.IsDisposed)
+            if (instance.State == SoundState.Stopped)
             {
-                instance.Dispose();
-                _activeSoundEffectInstances.RemoveAt(index);
+                if (!instance.IsDisposed)
+                {
+                    instance.Dispose();
+                }
+                _activeSoundEffectInstances.RemoveAt(i);
             }
-            index++;
         }
     }
 
diff --git a/Tutorials/learn-monogame-2d/src/18-Texture-Wrapping/MonoGameLibrary/Audio/AudioController.cs b/Tutorials/learn-monogame-2d/src/18-Texture-Wrapping/MonoGameLibrary/Audio/AudioController.cs
index 7126c8d3..02a5759b 100644
--- a/Tutorials/learn-monogame-2d/src/18-Texture-Wrapping/MonoGameLibrary/Audio/AudioController.cs
+++ b/Tutorials/learn-monogame-2d/src/18-Texture-Wrapping/MonoGameLibrary/Audio/AudioController.cs
@@ -100,18 +100,18 @@ public AudioController()
     /// </summary>
     public void Update()
     {
-        int index = 0;
-
-        while (index < _activeSoundEffectInstances.Count)
+        for (int i = _activeSoundEffectInstances.Count - 1; i >= 0; i--)
         {
-            SoundEffectInstance instance = _activeSoundEffectInstances[index];
+            SoundEffectInstance instance = _activeSoundEffectInstances[i];
 
-            if (instance.State == SoundState.Stopped && !instance.IsDisposed)
+            if (instance.State == SoundState.Stopped)
             {
-                instance.Dispose();
-                _activeSoundEffectInstances.RemoveAt(index);
+                if (!instance.IsDisposed)
+                {
+                    instance.Dispose();
+                }
+                _activeSoundEffectInstances.RemoveAt(i);
             }
-            index++;
         }
     }
 
diff --git a/Tutorials/learn-monogame-2d/src/19-User-Interface-Fundamentals/MonoGameLibrary/Audio/AudioController.cs b/Tutorials/learn-monogame-2d/src/19-User-Interface-Fundamentals/MonoGameLibrary/Audio/AudioController.cs
index 7126c8d3..02a5759b 100644
--- a/Tutorials/learn-monogame-2d/src/19-User-Interface-Fundamentals/MonoGameLibrary/Audio/AudioController.cs
+++ b/Tutorials/learn-monogame-2d/src/19-User-Interface-Fundamentals/MonoGameLibrary/Audio/AudioController.cs
@@ -100,18 +100,18 @@ public AudioController()
     /// </summary>
     public void Update()
     {
-        int index = 0;
-
-        while (index < _activeSoundEffectInstances.Count)
+        for (int i = _activeSoundEffectInstances.Count - 1; i >= 0; i--)
         {
-            SoundEffectInstance instance = _activeSoundEffectInstances[index];
+            SoundEffectInstance instance = _activeSoundEffectInstances[i];
 
-            if (instance.State == SoundState.Stopped && !instance.IsDisposed)
+            if (instance.State == SoundState.Stopped)
             {
-                instance.Dispose();
-                _activeSoundEffectInstances.RemoveAt(index);
+                if (!instance.IsDisposed)
+                {
+                    instance.Dispose();
+                }
+                _activeSoundEffectInstances.RemoveAt(i);
             }
-            index++;
         }
     }
 
diff --git a/Tutorials/learn-monogame-2d/src/20-Implementing-UI-With-Gum/MonoGameLibrary/Audio/AudioController.cs b/Tutorials/learn-monogame-2d/src/20-Implementing-UI-With-Gum/MonoGameLibrary/Audio/AudioController.cs
index 7126c8d3..02a5759b 100644
--- a/Tutorials/learn-monogame-2d/src/20-Implementing-UI-With-Gum/MonoGameLibrary/Audio/AudioController.cs
+++ b/Tutorials/learn-monogame-2d/src/20-Implementing-UI-With-Gum/MonoGameLibrary/Audio/AudioController.cs
@@ -100,18 +100,18 @@ public AudioController()
     /// </summary>
     public void Update()
     {
-        int index = 0;
-
-        while (index < _activeSoundEffectInstances.Count)
+        for (int i = _activeSoundEffectInstances.Count - 1; i >= 0; i--)
         {
-            SoundEffectInstance instance = _activeSoundEffectInstances[index];
+            SoundEffectInstance instance = _activeSoundEffectInstances[i];
 
-            if (instance.State == SoundState.Stopped && !instance.IsDisposed)
+            if (instance.State == SoundState.Stopped)
             {
-                instance.Dispose();
-                _activeSoundEffectInstances.RemoveAt(index);
+                if (!instance.IsDisposed)
+                {
+                    instance.Dispose();
+                }
+                _activeSoundEffectInstances.RemoveAt(i);
             }
-            index++;
         }
     }
 
diff --git a/Tutorials/learn-monogame-2d/src/21-Customizing-Gum-UI/MonoGameLibrary/Audio/AudioController.cs b/Tutorials/learn-monogame-2d/src/21-Customizing-Gum-UI/MonoGameLibrary/Audio/AudioController.cs
index 7126c8d3..02a5759b 100644
--- a/Tutorials/learn-monogame-2d/src/21-Customizing-Gum-UI/MonoGameLibrary/Audio/AudioController.cs
+++ b/Tutorials/learn-monogame-2d/src/21-Customizing-Gum-UI/MonoGameLibrary/Audio/AudioController.cs
@@ -100,18 +100,18 @@ public AudioController()
     /// </summary>
     public void Update()
     {
-        int index = 0;
-
-        while (index < _activeSoundEffectInstances.Count)
+        for (int i = _activeSoundEffectInstances.Count - 1; i >= 0; i--)
         {
-            SoundEffectInstance instance = _activeSoundEffectInstances[index];
+            SoundEffectInstance instance = _activeSoundEffectInstances[i];
 
-            if (instance.State == SoundState.Stopped && !instance.IsDisposed)
+            if (instance.State == SoundState.Stopped)
             {
-                instance.Dispose();
-                _activeSoundEffectInstances.RemoveAt(index);
+                if (!instance.IsDisposed)
+                {
+                    instance.Dispose();
+                }
+                _activeSoundEffectInstances.RemoveAt(i);
             }
-            index++;
         }
     }
 
diff --git a/Tutorials/learn-monogame-2d/src/22-Snake-Game-Mechanics/MonoGameLibrary/Audio/AudioController.cs b/Tutorials/learn-monogame-2d/src/22-Snake-Game-Mechanics/MonoGameLibrary/Audio/AudioController.cs
index 7126c8d3..13ba764c 100644
--- a/Tutorials/learn-monogame-2d/src/22-Snake-Game-Mechanics/MonoGameLibrary/Audio/AudioController.cs
+++ b/Tutorials/learn-monogame-2d/src/22-Snake-Game-Mechanics/MonoGameLibrary/Audio/AudioController.cs
@@ -97,21 +97,21 @@ public AudioController()
 
     /// <summary>
     /// Updates this audio controller
-    /// </summary>
+        /// </summary>
     public void Update()
     {
-        int index = 0;
-
-        while (index < _activeSoundEffectInstances.Count)
+        for (int i = _activeSoundEffectInstances.Count - 1; i >= 0; i--)
         {
-            SoundEffectInstance instance = _activeSoundEffectInstances[index];
+            SoundEffectInstance instance = _activeSoundEffectInstances[i];
 
-            if (instance.State == SoundState.Stopped && !instance.IsDisposed)
+            if (instance.State == SoundState.Stopped)
             {
-                instance.Dispose();
-                _activeSoundEffectInstances.RemoveAt(index);
+                if (!instance.IsDisposed)
+                {
+                    instance.Dispose();
+                }
+                _activeSoundEffectInstances.RemoveAt(i);
             }
-            index++;
         }
     }
 
diff --git a/Tutorials/learn-monogame-2d/src/23-Completing-The-Game/MonoGameLibrary/Audio/AudioController.cs b/Tutorials/learn-monogame-2d/src/23-Completing-The-Game/MonoGameLibrary/Audio/AudioController.cs
index 7126c8d3..02a5759b 100644
--- a/Tutorials/learn-monogame-2d/src/23-Completing-The-Game/MonoGameLibrary/Audio/AudioController.cs
+++ b/Tutorials/learn-monogame-2d/src/23-Completing-The-Game/MonoGameLibrary/Audio/AudioController.cs
@@ -100,18 +100,18 @@ public AudioController()
     /// </summary>
     public void Update()
     {
-        int index = 0;
-
-        while (index < _activeSoundEffectInstances.Count)
+        for (int i = _activeSoundEffectInstances.Count - 1; i >= 0; i--)
         {
-            SoundEffectInstance instance = _activeSoundEffectInstances[index];
+            SoundEffectInstance instance = _activeSoundEffectInstances[i];
 
-            if (instance.State == SoundState.Stopped && !instance.IsDisposed)
+            if (instance.State == SoundState.Stopped)
             {
-                instance.Dispose();
-                _activeSoundEffectInstances.RemoveAt(index);
+                if (!instance.IsDisposed)
+                {
+                    instance.Dispose();
+                }
+                _activeSoundEffectInstances.RemoveAt(i);
             }
-            index++;
         }
     }
 
diff --git a/Tutorials/learn-monogame-2d/src/24-Shaders/MonoGameLibrary/Audio/AudioController.cs b/Tutorials/learn-monogame-2d/src/24-Shaders/MonoGameLibrary/Audio/AudioController.cs
index 7126c8d3..02a5759b 100644
--- a/Tutorials/learn-monogame-2d/src/24-Shaders/MonoGameLibrary/Audio/AudioController.cs
+++ b/Tutorials/learn-monogame-2d/src/24-Shaders/MonoGameLibrary/Audio/AudioController.cs
@@ -100,18 +100,18 @@ public AudioController()
     /// </summary>
     public void Update()
     {
-        int index = 0;
-
-        while (index < _activeSoundEffectInstances.Count)
+        for (int i = _activeSoundEffectInstances.Count - 1; i >= 0; i--)
         {
-            SoundEffectInstance instance = _activeSoundEffectInstances[index];
+            SoundEffectInstance instance = _activeSoundEffectInstances[i];
 
-            if (instance.State == SoundState.Stopped && !instance.IsDisposed)
+            if (instance.State == SoundState.Stopped)
             {
-                instance.Dispose();
-                _activeSoundEffectInstances.RemoveAt(index);
+                if (!instance.IsDisposed)
+                {
+                    instance.Dispose();
+                }
+                _activeSoundEffectInstances.RemoveAt(i);
             }
-            index++;
         }
     }
 
diff --git a/Tutorials/learn-monogame-2d/src/25-Packaging-Game/MonoGameLibrary/Audio/AudioController.cs b/Tutorials/learn-monogame-2d/src/25-Packaging-Game/MonoGameLibrary/Audio/AudioController.cs
index 7126c8d3..02a5759b 100644
--- a/Tutorials/learn-monogame-2d/src/25-Packaging-Game/MonoGameLibrary/Audio/AudioController.cs
+++ b/Tutorials/learn-monogame-2d/src/25-Packaging-Game/MonoGameLibrary/Audio/AudioController.cs
@@ -100,18 +100,18 @@ public AudioController()
     /// </summary>
     public void Update()
     {
-        int index = 0;
-
-        while (index < _activeSoundEffectInstances.Count)
+        for (int i = _activeSoundEffectInstances.Count - 1; i >= 0; i--)
         {
-            SoundEffectInstance instance = _activeSoundEffectInstances[index];
+            SoundEffectInstance instance = _activeSoundEffectInstances[i];
 
-            if (instance.State == SoundState.Stopped && !instance.IsDisposed)
+            if (instance.State == SoundState.Stopped)
             {
-                instance.Dispose();
-                _activeSoundEffectInstances.RemoveAt(index);
+                if (!instance.IsDisposed)
+                {
+                    instance.Dispose();
+                }
+                _activeSoundEffectInstances.RemoveAt(i);
             }
-            index++;
         }
     }
 
diff --git a/Tutorials/learn-monogame-2d/src/26-Publish-To-Itch/MonoGameLibrary/Audio/AudioController.cs b/Tutorials/learn-monogame-2d/src/26-Publish-To-Itch/MonoGameLibrary/Audio/AudioController.cs
index 7126c8d3..02a5759b 100644
--- a/Tutorials/learn-monogame-2d/src/26-Publish-To-Itch/MonoGameLibrary/Audio/AudioController.cs
+++ b/Tutorials/learn-monogame-2d/src/26-Publish-To-Itch/MonoGameLibrary/Audio/AudioController.cs
@@ -100,18 +100,18 @@ public AudioController()
     /// </summary>
     public void Update()
     {
-        int index = 0;
-
-        while (index < _activeSoundEffectInstances.Count)
+        for (int i = _activeSoundEffectInstances.Count - 1; i >= 0; i--)
         {
-            SoundEffectInstance instance = _activeSoundEffectInstances[index];
+            SoundEffectInstance instance = _activeSoundEffectInstances[i];
 
-            if (instance.State == SoundState.Stopped && !instance.IsDisposed)
+            if (instance.State == SoundState.Stopped)
             {
-                instance.Dispose();
-                _activeSoundEffectInstances.RemoveAt(index);
+                if (!instance.IsDisposed)
+                {
+                    instance.Dispose();
+                }
+                _activeSoundEffectInstances.RemoveAt(i);
             }
-            index++;
         }
     }
 
diff --git a/Tutorials/learn-monogame-2d/src/27-Conclusion/MonoGameLibrary/Audio/AudioController.cs b/Tutorials/learn-monogame-2d/src/27-Conclusion/MonoGameLibrary/Audio/AudioController.cs
index 7126c8d3..02a5759b 100644
--- a/Tutorials/learn-monogame-2d/src/27-Conclusion/MonoGameLibrary/Audio/AudioController.cs
+++ b/Tutorials/learn-monogame-2d/src/27-Conclusion/MonoGameLibrary/Audio/AudioController.cs
@@ -100,18 +100,18 @@ public AudioController()
     /// </summary>
     public void Update()
     {
-        int index = 0;
-
-        while (index < _activeSoundEffectInstances.Count)
+        for (int i = _activeSoundEffectInstances.Count - 1; i >= 0; i--)
         {
-            SoundEffectInstance instance = _activeSoundEffectInstances[index];
+            SoundEffectInstance instance = _activeSoundEffectInstances[i];
 
-            if (instance.State == SoundState.Stopped && !instance.IsDisposed)
+            if (instance.State == SoundState.Stopped)
             {
-                instance.Dispose();
-                _activeSoundEffectInstances.RemoveAt(index);
+                if (!instance.IsDisposed)
+                {
+                    instance.Dispose();
+                }
+                _activeSoundEffectInstances.RemoveAt(i);
             }
-            index++;
         }
     }