Major updates to the echo removal functionality in AEC3

webrtc/modules/audio_processing/aec3/comfort_noise_generator.cc

Index: webrtc/modules/audio_processing/aec3/comfort_noise_generator.cc
diff --git a/webrtc/modules/audio_processing/aec3/comfort_noise_generator.cc b/webrtc/modules/audio_processing/aec3/comfort_noise_generator.cc
index f630b25175eb3b22ef2ee3ee6cfa47f256a0434c..b8d7f28df6b402543fdda02d671b2983ddc319d1 100644
--- a/webrtc/modules/audio_processing/aec3/comfort_noise_generator.cc
+++ b/webrtc/modules/audio_processing/aec3/comfort_noise_generator.cc
@@ -188,6 +188,17 @@ void ComfortNoiseGenerator::Compute(
     }
   }
 
+  // Limit the noise to a floor of -96 dBFS.
+  constexpr float kNoiseFloor = 440.f;
+  for (auto& n : N2_) {
+    n = std::max(n, kNoiseFloor);
+  }
+  if (N2_initial_) {
+    for (auto& n : *N2_initial_) {
+      n = std::max(n, kNoiseFloor);
+    }
+  }
+
   // Choose N2 estimate to use.
   const std::array<float, kFftLengthBy2Plus1>& N2 =
       N2_initial_ ? *N2_initial_ : N2_;