Changes to the sideband activity filter

Issue #390 I changed the way the event filter is working that filters on acoustic activity in the sidebands. I changed the name of a variable and its function. The sidebnad filter now checks for two kinds of sideband activity - the average background decibels in the sidebands, and it looks for brief events in the sidebands.

src/AnalysisConfigFiles/RecognizerConfigFiles/Towsey.AnthusNovaeseelandiae.yml

@@ -64,7 +64,7 @@ PostProcessing:
     SidebandActivity:
         LowerHertzBuffer: 0 #200
         UpperHertzBuffer: 0
-        DecibelBuffer: 0.0 #9.0
+        MaxAverageSidebandDecibels: 0.0 #9.0
 
 # Options to save results files
 # 1: Available options for saving spectrograms (case-sensitive): [False/Never | True/Always | WhenEventsDetected]

src/AnalysisConfigFiles/RecognizerConfigFiles/Towsey.BotaurusPoiciloptilus.yml

@@ -73,7 +73,7 @@ PostProcessing:
     SidebandActivity:
         LowerHertzBuffer: 150
         UpperHertzBuffer: 200
-        DecibelBuffer: 6.0
+        MaxAverageSidebandDecibels: 6.0
 
 # Options to save results files
 # 1: Available options for saving spectrograms (case-sensitive): [False/Never | True/Always | WhenEventsDetected]

src/AnalysisConfigFiles/RecognizerConfigFiles/Towsey.CisticolaExilis.yml

@@ -64,7 +64,7 @@ PostProcessing:
     SidebandActivity:
         LowerHertzBuffer: 0
         UpperHertzBuffer: 200
-        DecibelBuffer: 2.0
+        MaxAverageSidebandDecibels: 2.0
 
 # Options to save results files
 # 1: Available options for saving spectrograms (case-sensitive): [False/Never | True/Always | WhenEventsDetected]

src/AnalysisConfigFiles/RecognizerConfigFiles/Towsey.NinoxBoobook.yml

@@ -65,7 +65,7 @@ PostProcessing:
     SidebandActivity:
         LowerHertzBuffer: 150
         UpperHertzBuffer: 400
-        DecibelBuffer: 0.0
+        MaxAverageSidebandDecibels: 3.0
 
 # Options to save results files
 # 1: Available options for saving spectrograms (case-sensitive): [False/Never | True/Always | WhenEventsDetected]

src/AnalysisConfigFiles/RecognizerConfigFiles/Towsey.NinoxStrenua.yml

@@ -22,6 +22,7 @@ DecibelThresholds:
     - 18.0
     - 24.0
     - 30.0
+    - 36.0
 
 # Each of these profiles will be analyzed
 # This profile is required for the species-specific recogniser and must have the current name.
@@ -36,8 +37,8 @@ Profiles:
         # min and max of the freq band to search
         MinHertz: 300          
         MaxHertz: 600
-        MinDuration: 0.2
-        MaxDuration: 0.9
+        MinDuration: 0.3
+        MaxDuration: 0.6
 
 #################### POST-PROCESSING of EVENTS ###################
 
@@ -54,7 +55,7 @@ PostProcessing:
     # 2: Combine possible syllable sequences
     SyllableSequence:
         CombinePossibleSyllableSequence: true
-        SyllableStartDifference: 1.4
+        SyllableStartDifference: 0.7
         SyllableHertzGap: 100
         FilterSyllableSequence: false
         SyllableMaxCount: 6
@@ -74,7 +75,7 @@ PostProcessing:
     SidebandActivity:
         LowerHertzBuffer: 0
         UpperHertzBuffer: 0
-        DecibelBuffer: 3.0   # use this value when combining sequences
+        MaxAverageSidebandDecibels: 3.0
 
 # Various options to save results files
 # 1: Available options for saving spectrograms (case-sensitive): [False/Never | True/Always | WhenEventsDetected]

src/AudioAnalysisTools/Events/EventFilters.cs

@@ -295,22 +295,25 @@ public static (int Count, double AveragePeriod, double SdPeriod) GetPeriodicity(
         /// <param name="spectrogram">A matrix of the spectrogram in which event occurs.</param>
         /// <param name="lowerHertzBuffer">The band width of the required lower buffer. 100-200Hz is often appropriate.</param>
         /// <param name="upperHertzBuffer">The band width of the required upper buffer. 300-500Hz is often appropriate.</param>
-        /// <param name="decibelThreshold">The decibel threshold for acoustic activity in a sideband.</param>
+        /// <param name="thresholdForAverageDecibelsInSidebands">The max allowed value for the average decibels value (over all spectrogram cells) in a sideband of an event.</param>
         /// <param name="segmentStartOffset">Start time of the current recording segment.</param>
         /// <returns>A list of filtered events.</returns>
         public static List<EventCommon> FilterEventsOnSidebandActivity(
             List<SpectralEvent> events,
-            double analysisThreshold,
             BaseSonogram spectrogram,
             int lowerHertzBuffer,
             int upperHertzBuffer,
-            double decibelThreshold,
+            double thresholdForAverageDecibelsInSidebands,
             TimeSpan segmentStartOffset)
         {
             // allow bin gaps below the event.
             int lowerBinGap = 2;
             int upperBinGap = 2;
 
+            //The decibel value of any other event in the sidebands of a focal event
+            // cannot come within 3 dB of the dB value of the focal event.
+            var decibelBuffer = 3.0;
+
             var converter = new UnitConverters(
                 segmentStartOffset: segmentStartOffset.TotalSeconds,
                 sampleRate: spectrogram.SampleRate,
@@ -323,27 +326,27 @@ public static List<EventCommon> FilterEventsOnSidebandActivity(
             foreach (var ev in events)
             {
                 var avEventDecibels = EventExtentions.GetAverageDecibelsInEvent(ev, spectrogramData, converter);
+                var maxSidebandEventDecibels = Math.Max(0.0, avEventDecibels - decibelBuffer);
+
                 var retainEvent1 = true;
                 var retainEvent2 = true;
 
                 if (lowerHertzBuffer > 0)
                 {
                     var lowerSidebandMatrix = GetLowerEventSideband(ev, spectrogramData, lowerHertzBuffer, lowerBinGap, converter);
                     retainEvent1 = IsSidebandActivityBelowThreshold(
-                        avEventDecibels,
-                        analysisThreshold,
                         lowerSidebandMatrix,
-                        decibelThreshold);
+                        maxSidebandEventDecibels,
+                        thresholdForAverageDecibelsInSidebands);
                 }
 
                 if (upperHertzBuffer > 0)
                 {
                     var upperSidebandMatrix = GetUpperEventSideband(ev, spectrogramData, upperHertzBuffer, upperBinGap, converter);
                     retainEvent2 = IsSidebandActivityBelowThreshold(
-                        avEventDecibels,
-                        analysisThreshold,
                         upperSidebandMatrix,
-                        decibelThreshold);
+                        maxSidebandEventDecibels,
+                        thresholdForAverageDecibelsInSidebands);
                 }
 
                 if (retainEvent1 && retainEvent2)
@@ -358,18 +361,17 @@ public static List<EventCommon> FilterEventsOnSidebandActivity(
         }
 
         public static bool IsSidebandActivityBelowThreshold(
-            double avEventDecibels,
-            double analysisThreshold,
             double[,] sidebandMatrix,
-            double sidebandThreshold)
+            double maxSidebandEventDecibels,
+            double thresholdForAverageDecibelsInSidebands)
         {
             var averageRowDecibels = MatrixTools.GetRowAverages(sidebandMatrix);
             var averageColDecibels = MatrixTools.GetColumnAverages(sidebandMatrix);
             var averageMatrixDecibels = averageColDecibels.Average();
 
             // Is the average acoustic activity in the sideband below the user set threshold?
             //bool avBgBelowThreshold = averageMatrixDecibels < analysisThreshold;
-            bool avBgBelowThreshold = averageMatrixDecibels < sidebandThreshold;
+            bool avBgBelowThreshold = averageMatrixDecibels < thresholdForAverageDecibelsInSidebands;
             if (!avBgBelowThreshold)
             {
                 return false;
@@ -378,8 +380,8 @@ public static bool IsSidebandActivityBelowThreshold(
             // Also need to cover possibility that there is much acoustic activity concentrated in one freq bin or time frame.
             // Therefore, also require that there be at most one sideband bin and one sideband frame containing acoustic activity
             // that is greater than the average in the event.
-            int noisyRowCount = averageRowDecibels.Count(x => x > avEventDecibels);
-            int noisyColCount = averageColDecibels.Count(x => x > avEventDecibels);
+            int noisyRowCount = averageRowDecibels.Count(x => x > maxSidebandEventDecibels);
+            int noisyColCount = averageColDecibels.Count(x => x > maxSidebandEventDecibels);
             bool doRetain = noisyRowCount <= 1 && noisyColCount <= 1;
             return doRetain;
         }

src/AudioAnalysisTools/Events/Types/EventPostProcessing.cs

@@ -18,7 +18,6 @@ public static class EventPostProcessing
 
         public static List<EventCommon> PostProcessingOfSpectralEvents(
             List<EventCommon> newEvents,
-            double analysisThreshold,
             PostProcessingConfig postprocessingConfig,
             BaseSonogram spectrogram,
             TimeSpan segmentStartOffset)
@@ -92,11 +91,10 @@ public static List<EventCommon> PostProcessingOfSpectralEvents(
                 var spectralEvents2 = newEvents.Cast<SpectralEvent>().ToList();
                 newEvents = EventFilters.FilterEventsOnSidebandActivity(
                     spectralEvents2,
-                    analysisThreshold,
                     spectrogram,
                     sidebandActivity.LowerHertzBuffer,
                     sidebandActivity.UpperHertzBuffer,
-                    sidebandActivity.DecibelBuffer,
+                    sidebandActivity.MaxAverageSidebandDecibels,
                     segmentStartOffset);
                 Log.Debug($"Event count after filtering on acoustic activity in sidebands = {newEvents.Count}");
             }
@@ -198,11 +196,11 @@ public class SidebandConfig
             public int LowerHertzBuffer { get; set; }
 
             /// <summary>
-            /// Gets or sets a value indicating the decibel gap/difference between acoustic activity in the event and in the upper and lower buffer zones.
-            /// BufferAcousticActivity must be LessThan (EventAcousticActivity - DecibelBuffer)
+            /// Gets or sets a value indicating the maximum value of the average decibels of acoustic activity
+            ///        in the upper and lower sidebands of an event. The average is over all spectrogram cells in each sideband.
             /// This value is used only if LowerHertzBuffer > 0 OR UpperHertzBuffer > 0.
             /// </summary>
-            public double DecibelBuffer { get; set; }
+            public double MaxAverageSidebandDecibels { get; set; }
         }
 
         /// <summary>