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diff --git a/third_party/libwebrtc/modules/audio_processing/ns/noise_estimator.h b/third_party/libwebrtc/modules/audio_processing/ns/noise_estimator.h
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+/*
+ *  Copyright (c) 2019 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef MODULES_AUDIO_PROCESSING_NS_NOISE_ESTIMATOR_H_
+#define MODULES_AUDIO_PROCESSING_NS_NOISE_ESTIMATOR_H_
+
+#include <array>
+
+#include "api/array_view.h"
+#include "modules/audio_processing/ns/ns_common.h"
+#include "modules/audio_processing/ns/quantile_noise_estimator.h"
+#include "modules/audio_processing/ns/suppression_params.h"
+
+namespace webrtc {
+
+// Class for estimating the spectral characteristics of the noise in an incoming
+// signal.
+class NoiseEstimator {
+ public:
+  explicit NoiseEstimator(const SuppressionParams& suppression_params);
+
+  // Prepare the estimator for analysis of a new frame.
+  void PrepareAnalysis();
+
+  // Performs the first step of the estimator update.
+  void PreUpdate(int32_t num_analyzed_frames,
+                 rtc::ArrayView<const float, kFftSizeBy2Plus1> signal_spectrum,
+                 float signal_spectral_sum);
+
+  // Performs the second step of the estimator update.
+  void PostUpdate(
+      rtc::ArrayView<const float> speech_probability,
+      rtc::ArrayView<const float, kFftSizeBy2Plus1> signal_spectrum);
+
+  // Returns the noise spectral estimate.
+  rtc::ArrayView<const float, kFftSizeBy2Plus1> get_noise_spectrum() const {
+    return noise_spectrum_;
+  }
+
+  // Returns the noise from the previous frame.
+  rtc::ArrayView<const float, kFftSizeBy2Plus1> get_prev_noise_spectrum()
+      const {
+    return prev_noise_spectrum_;
+  }
+
+  // Returns a noise spectral estimate based on white and pink noise parameters.
+  rtc::ArrayView<const float, kFftSizeBy2Plus1> get_parametric_noise_spectrum()
+      const {
+    return parametric_noise_spectrum_;
+  }
+  rtc::ArrayView<const float, kFftSizeBy2Plus1>
+  get_conservative_noise_spectrum() const {
+    return conservative_noise_spectrum_;
+  }
+
+ private:
+  const SuppressionParams& suppression_params_;
+  float white_noise_level_ = 0.f;
+  float pink_noise_numerator_ = 0.f;
+  float pink_noise_exp_ = 0.f;
+  std::array<float, kFftSizeBy2Plus1> prev_noise_spectrum_;
+  std::array<float, kFftSizeBy2Plus1> conservative_noise_spectrum_;
+  std::array<float, kFftSizeBy2Plus1> parametric_noise_spectrum_;
+  std::array<float, kFftSizeBy2Plus1> noise_spectrum_;
+  QuantileNoiseEstimator quantile_noise_estimator_;
+};
+
+}  // namespace webrtc
+
+#endif  // MODULES_AUDIO_PROCESSING_NS_NOISE_ESTIMATOR_H_