Open end working

Core/SoundProcessor.cs

@@ -1,18 +1,20 @@
 using System;
-using FluidSim.Interfaces;
+using FluidSim.Core;
 
 namespace FluidSim.Core
 {
     public class SoundProcessor
     {
         private readonly double dt;
-        private readonly double scaleFactor;  // 1 / (4π r) and a user gain
+        private readonly double scaleFactor;  // 1 / (4π r)
         private double prevMassFlowOut;
-
-        // Simple low‑pass for derivative smoothing (≈ 2‑3 ms)
         private double smoothDMdt;
         private readonly double alpha;
 
+        // New: low‑pass the mass flow signal before derivative
+        private double flowLP;
+        private readonly double lpAlpha;
+
         public float Gain { get; set; } = 1.0f;
 
         public SoundProcessor(int sampleRate, double listenerDistanceMeters = 1.0)
@@ -20,29 +22,34 @@ namespace FluidSim.Core
             dt = 1.0 / sampleRate;
             scaleFactor = 1.0 / (4.0 * Math.PI * listenerDistanceMeters);
 
-            // Smoothing time constant ~ 2 ms, blocks single‑sample spikes
-            double tau = 0.002;
+            // Smoothing time constant for the derivative: 10 ms (much smoother)
+            double tau = 0.010;   // 10 ms
             alpha = Math.Exp(-dt / tau);
+
+            // Low‑pass time constant for the mass flow: 5 ms (kneecap high‑freq directly)
+            double tauLP = 0.005;
+            lpAlpha = Math.Exp(-dt / tauLP);
         }
 
-        public float Process(Port port)
+        public float Process(OpenEndLink openEnd)
         {
-            // Outflow mass flow (positive = leaving pipe)
-            double flowOut = -port.MassFlowRate;
+            double flowOut = openEnd.LastMassFlowRate;
 
-            // Derivative
-            double rawDerivative = (flowOut - prevMassFlowOut) / dt;
-            prevMassFlowOut = flowOut;
+            // Low‑pass the mass flow signal
+            flowLP = lpAlpha * flowLP + (1.0 - lpAlpha) * flowOut;
 
-            // Smooth the derivative to kill isolated spikes
+            // Derivative of the smoothed mass flow
+            double rawDerivative = (flowLP - prevMassFlowOut) / dt;
+            prevMassFlowOut = flowLP;
+
+            // Smooth the derivative
             smoothDMdt = alpha * smoothDMdt + (1.0 - alpha) * rawDerivative;
 
             // Far‑field monopole pressure
             double pressure = smoothDMdt * scaleFactor * Gain;
 
-            // Soft clip to ±1 for audio output (safe limit)
-            float sample = (float)Math.Tanh(pressure);
-            return sample;
+            // Soft clip to ±1 (should rarely trigger now)
+            return (float)Math.Tanh(pressure);
         }
     }
 }