Let us start here, from square one. No, from Zero!

hooks/audio/audio_private.h

@@ -0,0 +1,14 @@
+#pragma once
+
+#include <mutex>
+
+#include <windows.h>
+#include <audioclient.h>
+
+constexpr bool AUDIO_LOG_HRESULT = true;
+
+namespace hooks::audio {
+
+    extern IAudioClient *CLIENT;
+    extern std::mutex INITIALIZE_LOCK;
+}