AudioIO does not depend directly on ControlToolBar ...

... use one more callback in the listener to change the ControlToolBar pause
state.

src/AudioIO.cpp

@@ -462,7 +462,6 @@ time warp info and AudioIOListener and whether the playback is looped.
 #include "effects/RealtimeEffectManager.h"
 #include "prefs/QualityPrefs.h"
 #include "prefs/RecordingPrefs.h"
-#include "toolbars/ControlToolBar.h"
 #include "widgets/MeterPanelBase.h"
 #include "widgets/AudacityMessageBox.h"
 #include "widgets/ErrorDialog.h"
@@ -3692,8 +3691,8 @@ void AudioIoCallback::CheckSoundActivatedRecordingLevel( const void *inputBuffer
    bool bShouldBePaused = mInputMeter->GetMaxPeak() < mSilenceLevel;
    if( bShouldBePaused != IsPaused())
    {
-      auto &bar = ControlToolBar::Get( *mOwningProject );
-      bar.CallAfter(&ControlToolBar::Pause);
+      if ( mListener )
+         mListener->OnSoundActivationThreshold();
    }
 }
 

src/AudioIOListener.h

@@ -32,6 +32,10 @@ public:
    // Commit the addition of temporary recording tracks into the project
    virtual void OnCommitRecording() = 0;
 
+   // During recording, the threshold for sound activation has been crossed
+   // in either direction
+   virtual void OnSoundActivationThreshold() = 0;
+
 };
 
 #endif

src/ProjectAudioManager.cpp

@@ -181,6 +181,16 @@ void ProjectAudioManager::OnCommitRecording()
    TrackList::Get( *project ).ApplyPendingTracks();
 }
 
+void ProjectAudioManager::OnSoundActivationThreshold()
+{
+   auto &project = mProject;
+   auto gAudioIO = AudioIO::Get();
+   if ( gAudioIO && &project == gAudioIO->GetOwningProject() ) {
+      auto &bar = ControlToolBar::Get( project );
+      bar.CallAfter(&ControlToolBar::Pause);
+   }
+}
+
 AudioIOStartStreamOptions
 DefaultPlayOptions( AudacityProject &project )
 {

src/ProjectAudioManager.h

@@ -41,6 +41,7 @@ private:
    void OnAudioIOStopRecording() override;
    void OnAudioIONewBlockFiles(const AutoSaveFile & blockFileLog) override;
    void OnCommitRecording() override;
+   void OnSoundActivationThreshold() override;
 
    AudacityProject &mProject;