diff --git a/modules/audio_processing/agc2/rnn_vad/BUILD.gn b/modules/audio_processing/agc2/rnn_vad/BUILD.gn
index 237c809..7379d41 100644
--- a/modules/audio_processing/agc2/rnn_vad/BUILD.gn
+++ b/modules/audio_processing/agc2/rnn_vad/BUILD.gn
@@ -11,8 +11,6 @@
 rtc_source_set("rnn_vad") {
   visibility = [ "../*" ]
   sources = [
-    "auto_correlation.cc",
-    "auto_correlation.h",
     "common.h",
     "features_extraction.cc",
     "features_extraction.h",
@@ -39,9 +37,9 @@
     "..:biquad_filter",
     "../../../../api:array_view",
     "../../../../api:function_view",
+    "../../../../common_audio/",
     "../../../../rtc_base:checks",
     "../../../../rtc_base:rtc_base_approved",
-    "../../utility:pffft_wrapper",
     "//third_party/rnnoise:kiss_fft",
     "//third_party/rnnoise:rnn_vad",
   ]
@@ -55,7 +53,6 @@
       "test_utils.h",
     ]
     deps = [
-      ":rnn_vad",
       "../../../../api:array_view",
       "../../../../api:scoped_refptr",
       "../../../../rtc_base:checks",
@@ -89,7 +86,6 @@
   rtc_source_set("unittests") {
     testonly = true
     sources = [
-      "auto_correlation_unittest.cc",
       "features_extraction_unittest.cc",
       "fft_util_unittest.cc",
       "lp_residual_unittest.cc",
diff --git a/modules/audio_processing/agc2/rnn_vad/auto_correlation.cc b/modules/audio_processing/agc2/rnn_vad/auto_correlation.cc
deleted file mode 100644
index d932c78..0000000
--- a/modules/audio_processing/agc2/rnn_vad/auto_correlation.cc
+++ /dev/null
@@ -1,92 +0,0 @@
-/*
- *  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.
- */
-
-#include "modules/audio_processing/agc2/rnn_vad/auto_correlation.h"
-
-#include <algorithm>
-
-#include "rtc_base/checks.h"
-
-namespace webrtc {
-namespace rnn_vad {
-namespace {
-
-constexpr int kAutoCorrelationFftOrder = 9;  // Length-512 FFT.
-static_assert(1 << kAutoCorrelationFftOrder >
-                  kNumInvertedLags12kHz + kBufSize12kHz - kMaxPitch12kHz,
-              "");
-
-}  // namespace
-
-AutoCorrelationCalculator::AutoCorrelationCalculator()
-    : fft_(1 << kAutoCorrelationFftOrder, Pffft::FftType::kReal),
-      tmp_(fft_.CreateBuffer()),
-      X_(fft_.CreateBuffer()),
-      H_(fft_.CreateBuffer()) {}
-
-AutoCorrelationCalculator::~AutoCorrelationCalculator() = default;
-
-// The auto-correlations coefficients are computed as follows:
-// |.........|...........|  <- pitch buffer
-//           [ x (fixed) ]
-// [   y_0   ]
-//         [ y_{m-1} ]
-// x and y are sub-array of equal length; x is never moved, whereas y slides.
-// The cross-correlation between y_0 and x corresponds to the auto-correlation
-// for the maximum pitch period. Hence, the first value in |auto_corr| has an
-// inverted lag equal to 0 that corresponds to a lag equal to the maximum
-// pitch period.
-void AutoCorrelationCalculator::ComputeOnPitchBuffer(
-    rtc::ArrayView<const float, kBufSize12kHz> pitch_buf,
-    rtc::ArrayView<float, kNumInvertedLags12kHz> auto_corr) {
-  RTC_DCHECK_LT(auto_corr.size(), kMaxPitch12kHz);
-  RTC_DCHECK_GT(pitch_buf.size(), kMaxPitch12kHz);
-  constexpr size_t kFftFrameSize = 1 << kAutoCorrelationFftOrder;
-  constexpr size_t kConvolutionLength = kBufSize12kHz - kMaxPitch12kHz;
-  static_assert(kConvolutionLength == kFrameSize20ms12kHz,
-                "Mismatch between pitch buffer size, frame size and maximum "
-                "pitch period.");
-  static_assert(kFftFrameSize > kNumInvertedLags12kHz + kConvolutionLength,
-                "The FFT length is not sufficiently big to avoid cyclic "
-                "convolution errors.");
-  auto tmp = tmp_->GetView();
-
-  // Compute the FFT for the reversed reference frame - i.e.,
-  // pitch_buf[-kConvolutionLength:].
-  std::reverse_copy(pitch_buf.end() - kConvolutionLength, pitch_buf.end(),
-                    tmp.begin());
-  std::fill(tmp.begin() + kConvolutionLength, tmp.end(), 0.f);
-  fft_.ForwardTransform(*tmp_, H_.get(), /*ordered=*/false);
-
-  // Compute the FFT for the sliding frames chunk. The sliding frames are
-  // defined as pitch_buf[i:i+kConvolutionLength] where i in
-  // [0, kNumInvertedLags12kHz). The chunk includes all of them, hence it is
-  // defined as pitch_buf[:kNumInvertedLags12kHz+kConvolutionLength].
-  std::copy(pitch_buf.begin(),
-            pitch_buf.begin() + kConvolutionLength + kNumInvertedLags12kHz,
-            tmp.begin());
-  std::fill(tmp.begin() + kNumInvertedLags12kHz + kConvolutionLength, tmp.end(),
-            0.f);
-  fft_.ForwardTransform(*tmp_, X_.get(), /*ordered=*/false);
-
-  // Convolve in the frequency domain.
-  constexpr float kScalingFactor = 1.f / static_cast<float>(kFftFrameSize);
-  std::fill(tmp.begin(), tmp.end(), 0.f);
-  fft_.FrequencyDomainConvolve(*X_, *H_, tmp_.get(), kScalingFactor);
-  fft_.BackwardTransform(*tmp_, tmp_.get(), /*ordered=*/false);
-
-  // Extract the auto-correlation coefficients.
-  std::copy(tmp.begin() + kConvolutionLength - 1,
-            tmp.begin() + kConvolutionLength + kNumInvertedLags12kHz - 1,
-            auto_corr.begin());
-}
-
-}  // namespace rnn_vad
-}  // namespace webrtc
diff --git a/modules/audio_processing/agc2/rnn_vad/auto_correlation.h b/modules/audio_processing/agc2/rnn_vad/auto_correlation.h
deleted file mode 100644
index de7f453..0000000
--- a/modules/audio_processing/agc2/rnn_vad/auto_correlation.h
+++ /dev/null
@@ -1,49 +0,0 @@
-/*
- *  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_AGC2_RNN_VAD_AUTO_CORRELATION_H_
-#define MODULES_AUDIO_PROCESSING_AGC2_RNN_VAD_AUTO_CORRELATION_H_
-
-#include <memory>
-
-#include "api/array_view.h"
-#include "modules/audio_processing/agc2/rnn_vad/common.h"
-#include "modules/audio_processing/utility/pffft_wrapper.h"
-
-namespace webrtc {
-namespace rnn_vad {
-
-// Class to compute the auto correlation on the pitch buffer for a target pitch
-// interval.
-class AutoCorrelationCalculator {
- public:
-  AutoCorrelationCalculator();
-  AutoCorrelationCalculator(const AutoCorrelationCalculator&) = delete;
-  AutoCorrelationCalculator& operator=(const AutoCorrelationCalculator&) =
-      delete;
-  ~AutoCorrelationCalculator();
-
-  // Computes the auto-correlation coefficients for a target pitch interval.
-  // |auto_corr| indexes are inverted lags.
-  void ComputeOnPitchBuffer(
-      rtc::ArrayView<const float, kBufSize12kHz> pitch_buf,
-      rtc::ArrayView<float, kNumInvertedLags12kHz> auto_corr);
-
- private:
-  Pffft fft_;
-  std::unique_ptr<Pffft::FloatBuffer> tmp_;
-  std::unique_ptr<Pffft::FloatBuffer> X_;
-  std::unique_ptr<Pffft::FloatBuffer> H_;
-};
-
-}  // namespace rnn_vad
-}  // namespace webrtc
-
-#endif  // MODULES_AUDIO_PROCESSING_AGC2_RNN_VAD_AUTO_CORRELATION_H_
diff --git a/modules/audio_processing/agc2/rnn_vad/auto_correlation_unittest.cc b/modules/audio_processing/agc2/rnn_vad/auto_correlation_unittest.cc
deleted file mode 100644
index a5e456a..0000000
--- a/modules/audio_processing/agc2/rnn_vad/auto_correlation_unittest.cc
+++ /dev/null
@@ -1,62 +0,0 @@
-/*
- *  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.
- */
-
-#include "modules/audio_processing/agc2/rnn_vad/auto_correlation.h"
-
-#include "modules/audio_processing/agc2/rnn_vad/pitch_search_internal.h"
-#include "modules/audio_processing/agc2/rnn_vad/test_utils.h"
-#include "test/gtest.h"
-
-namespace webrtc {
-namespace rnn_vad {
-namespace test {
-
-TEST(RnnVadTest, PitchBufferAutoCorrelationWithinTolerance) {
-  PitchTestData test_data;
-  std::array<float, kBufSize12kHz> pitch_buf_decimated;
-  Decimate2x(test_data.GetPitchBufView(), pitch_buf_decimated);
-  std::array<float, kNumPitchBufAutoCorrCoeffs> computed_output;
-  {
-    // TODO(bugs.webrtc.org/8948): Add when the issue is fixed.
-    // FloatingPointExceptionObserver fpe_observer;
-    AutoCorrelationCalculator auto_corr_calculator;
-    auto_corr_calculator.ComputeOnPitchBuffer(pitch_buf_decimated,
-                                              computed_output);
-  }
-  auto auto_corr_view = test_data.GetPitchBufAutoCorrCoeffsView();
-  ExpectNearAbsolute({auto_corr_view.data(), auto_corr_view.size()},
-                     computed_output, 3e-3f);
-}
-
-// Check that the auto correlation function computes the right thing for a
-// simple use case.
-TEST(RnnVadTest, CheckAutoCorrelationOnConstantPitchBuffer) {
-  // Create constant signal with no pitch.
-  std::array<float, kBufSize12kHz> pitch_buf_decimated;
-  std::fill(pitch_buf_decimated.begin(), pitch_buf_decimated.end(), 1.f);
-  std::array<float, kNumPitchBufAutoCorrCoeffs> computed_output;
-  {
-    // TODO(bugs.webrtc.org/8948): Add when the issue is fixed.
-    // FloatingPointExceptionObserver fpe_observer;
-    AutoCorrelationCalculator auto_corr_calculator;
-    auto_corr_calculator.ComputeOnPitchBuffer(pitch_buf_decimated,
-                                              computed_output);
-  }
-  // The expected output is constantly the length of the fixed 'x'
-  // array in ComputePitchAutoCorrelation.
-  std::array<float, kNumPitchBufAutoCorrCoeffs> expected_output;
-  std::fill(expected_output.begin(), expected_output.end(),
-            kBufSize12kHz - kMaxPitch12kHz);
-  ExpectNearAbsolute(expected_output, computed_output, 4e-5f);
-}
-
-}  // namespace test
-}  // namespace rnn_vad
-}  // namespace webrtc
diff --git a/modules/audio_processing/agc2/rnn_vad/common.h b/modules/audio_processing/agc2/rnn_vad/common.h
index 2f16cd4..b98438d 100644
--- a/modules/audio_processing/agc2/rnn_vad/common.h
+++ b/modules/audio_processing/agc2/rnn_vad/common.h
@@ -20,21 +20,18 @@
 constexpr size_t kFrameSize10ms24kHz = kSampleRate24kHz / 100;
 constexpr size_t kFrameSize20ms24kHz = kFrameSize10ms24kHz * 2;
 
-// Pitch buffer.
+// Pitch analysis params.
 constexpr size_t kMinPitch24kHz = kSampleRate24kHz / 800;   // 0.00125 s.
 constexpr size_t kMaxPitch24kHz = kSampleRate24kHz / 62.5;  // 0.016 s.
 constexpr size_t kBufSize24kHz = kMaxPitch24kHz + kFrameSize20ms24kHz;
 static_assert((kBufSize24kHz & 1) == 0, "The buffer size must be even.");
 
-// 24 kHz analysis.
 // Define a higher minimum pitch period for the initial search. This is used to
 // avoid searching for very short periods, for which a refinement step is
 // responsible.
 constexpr size_t kInitialMinPitch24kHz = 3 * kMinPitch24kHz;
 static_assert(kMinPitch24kHz < kInitialMinPitch24kHz, "");
 static_assert(kInitialMinPitch24kHz < kMaxPitch24kHz, "");
-static_assert(kMaxPitch24kHz > kInitialMinPitch24kHz, "");
-constexpr size_t kNumInvertedLags24kHz = kMaxPitch24kHz - kInitialMinPitch24kHz;
 
 // 12 kHz analysis.
 constexpr size_t kSampleRate12kHz = 12000;
@@ -43,10 +40,6 @@
 constexpr size_t kBufSize12kHz = kBufSize24kHz / 2;
 constexpr size_t kInitialMinPitch12kHz = kInitialMinPitch24kHz / 2;
 constexpr size_t kMaxPitch12kHz = kMaxPitch24kHz / 2;
-static_assert(kMaxPitch12kHz > kInitialMinPitch12kHz, "");
-// The inverted lags for the pitch interval [|kInitialMinPitch12kHz|,
-// |kMaxPitch12kHz|] are in the range [0, |kNumInvertedLags12kHz|].
-constexpr size_t kNumInvertedLags12kHz = kMaxPitch12kHz - kInitialMinPitch12kHz;
 
 // 48 kHz constants.
 constexpr size_t kMinPitch48kHz = kMinPitch24kHz * 2;
diff --git a/modules/audio_processing/agc2/rnn_vad/pitch_search.cc b/modules/audio_processing/agc2/rnn_vad/pitch_search.cc
index 1b3b459..aa0b751 100644
--- a/modules/audio_processing/agc2/rnn_vad/pitch_search.cc
+++ b/modules/audio_processing/agc2/rnn_vad/pitch_search.cc
@@ -19,7 +19,8 @@
 namespace rnn_vad {
 
 PitchEstimator::PitchEstimator()
-    : pitch_buf_decimated_(kBufSize12kHz),
+    : fft_(RealFourier::Create(kAutoCorrelationFftOrder)),
+      pitch_buf_decimated_(kBufSize12kHz),
       pitch_buf_decimated_view_(pitch_buf_decimated_.data(), kBufSize12kHz),
       auto_corr_(kNumInvertedLags12kHz),
       auto_corr_view_(auto_corr_.data(), kNumInvertedLags12kHz) {
@@ -33,16 +34,20 @@
     rtc::ArrayView<const float, kBufSize24kHz> pitch_buf) {
   // Perform the initial pitch search at 12 kHz.
   Decimate2x(pitch_buf, pitch_buf_decimated_view_);
-  auto_corr_calculator_.ComputeOnPitchBuffer(pitch_buf_decimated_view_,
-                                             auto_corr_view_);
+  // Compute auto-correlation terms.
+  ComputePitchAutoCorrelation(pitch_buf_decimated_view_, kMaxPitch12kHz,
+                              auto_corr_view_, fft_.get());
+
+  // Search for pitch at 12 kHz.
   std::array<size_t, 2> pitch_candidates_inv_lags = FindBestPitchPeriods(
       auto_corr_view_, pitch_buf_decimated_view_, kMaxPitch12kHz);
+
   // Refine the pitch period estimation.
   // The refinement is done using the pitch buffer that contains 24 kHz samples.
   // Therefore, adapt the inverted lags in |pitch_candidates_inv_lags| from 12
   // to 24 kHz.
-  pitch_candidates_inv_lags[0] *= 2;
-  pitch_candidates_inv_lags[1] *= 2;
+  for (size_t i = 0; i < pitch_candidates_inv_lags.size(); ++i)
+    pitch_candidates_inv_lags[i] *= 2;
   size_t pitch_inv_lag_48kHz =
       RefinePitchPeriod48kHz(pitch_buf, pitch_candidates_inv_lags);
   // Look for stronger harmonics to find the final pitch period and its gain.
diff --git a/modules/audio_processing/agc2/rnn_vad/pitch_search.h b/modules/audio_processing/agc2/rnn_vad/pitch_search.h
index 74133d0..5914535 100644
--- a/modules/audio_processing/agc2/rnn_vad/pitch_search.h
+++ b/modules/audio_processing/agc2/rnn_vad/pitch_search.h
@@ -15,7 +15,7 @@
 #include <vector>
 
 #include "api/array_view.h"
-#include "modules/audio_processing/agc2/rnn_vad/auto_correlation.h"
+#include "common_audio/real_fourier.h"
 #include "modules/audio_processing/agc2/rnn_vad/common.h"
 #include "modules/audio_processing/agc2/rnn_vad/pitch_info.h"
 #include "modules/audio_processing/agc2/rnn_vad/pitch_search_internal.h"
@@ -36,7 +36,7 @@
 
  private:
   PitchInfo last_pitch_48kHz_;
-  AutoCorrelationCalculator auto_corr_calculator_;
+  std::unique_ptr<RealFourier> fft_;
   std::vector<float> pitch_buf_decimated_;
   rtc::ArrayView<float, kBufSize12kHz> pitch_buf_decimated_view_;
   std::vector<float> auto_corr_;
diff --git a/modules/audio_processing/agc2/rnn_vad/pitch_search_internal.cc b/modules/audio_processing/agc2/rnn_vad/pitch_search_internal.cc
index 0561c37..7c17dfb 100644
--- a/modules/audio_processing/agc2/rnn_vad/pitch_search_internal.cc
+++ b/modules/audio_processing/agc2/rnn_vad/pitch_search_internal.cc
@@ -13,6 +13,7 @@
 #include <stdlib.h>
 #include <algorithm>
 #include <cmath>
+#include <complex>
 #include <cstddef>
 #include <numeric>
 
@@ -212,6 +213,64 @@
   }
 }
 
+void ComputePitchAutoCorrelation(
+    rtc::ArrayView<const float, kBufSize12kHz> pitch_buf,
+    size_t max_pitch_period,
+    rtc::ArrayView<float, kNumInvertedLags12kHz> auto_corr,
+    webrtc::RealFourier* fft) {
+  RTC_DCHECK_GT(max_pitch_period, auto_corr.size());
+  RTC_DCHECK_LT(max_pitch_period, pitch_buf.size());
+  RTC_DCHECK(fft);
+
+  constexpr size_t time_domain_fft_length = 1 << kAutoCorrelationFftOrder;
+  constexpr size_t freq_domain_fft_length = time_domain_fft_length / 2 + 1;
+
+  RTC_DCHECK_EQ(RealFourier::FftLength(fft->order()), time_domain_fft_length);
+  RTC_DCHECK_EQ(RealFourier::ComplexLength(fft->order()),
+                freq_domain_fft_length);
+
+  // Cross-correlation of y_i=pitch_buf[i:i+convolution_length] and
+  // x=pitch_buf[-convolution_length:] is equivalent to convolution of
+  // y_i and reversed(x). New notation: h=reversed(x), x=y.
+  std::array<float, time_domain_fft_length> h{};
+  std::array<float, time_domain_fft_length> x{};
+
+  const size_t convolution_length = kBufSize12kHz - max_pitch_period;
+  // Check that the FFT-length is big enough to avoid cyclic
+  // convolution errors.
+  RTC_DCHECK_GT(time_domain_fft_length,
+                kNumInvertedLags12kHz + convolution_length);
+
+  // h[0:convolution_length] is reversed pitch_buf[-convolution_length:].
+  std::reverse_copy(pitch_buf.end() - convolution_length, pitch_buf.end(),
+                    h.begin());
+
+  // x is pitch_buf[:kNumInvertedLags12kHz + convolution_length].
+  std::copy(pitch_buf.begin(),
+            pitch_buf.begin() + kNumInvertedLags12kHz + convolution_length,
+            x.begin());
+
+  // Shift to frequency domain.
+  std::array<std::complex<float>, freq_domain_fft_length> X{};
+  std::array<std::complex<float>, freq_domain_fft_length> H{};
+  fft->Forward(&x[0], &X[0]);
+  fft->Forward(&h[0], &H[0]);
+
+  // Convolve in frequency domain.
+  for (size_t i = 0; i < X.size(); ++i) {
+    X[i] *= H[i];
+  }
+
+  // Shift back to time domain.
+  std::array<float, time_domain_fft_length> x_conv_h;
+  fft->Inverse(&X[0], &x_conv_h[0]);
+
+  // Collect the result.
+  std::copy(x_conv_h.begin() + convolution_length - 1,
+            x_conv_h.begin() + convolution_length + kNumInvertedLags12kHz - 1,
+            auto_corr.begin());
+}
+
 std::array<size_t, 2> FindBestPitchPeriods(
     rtc::ArrayView<const float> auto_corr,
     rtc::ArrayView<const float> pitch_buf,
diff --git a/modules/audio_processing/agc2/rnn_vad/pitch_search_internal.h b/modules/audio_processing/agc2/rnn_vad/pitch_search_internal.h
index 6ccd165..aabf713 100644
--- a/modules/audio_processing/agc2/rnn_vad/pitch_search_internal.h
+++ b/modules/audio_processing/agc2/rnn_vad/pitch_search_internal.h
@@ -15,12 +15,25 @@
 #include <array>
 
 #include "api/array_view.h"
+#include "common_audio/real_fourier.h"
 #include "modules/audio_processing/agc2/rnn_vad/common.h"
 #include "modules/audio_processing/agc2/rnn_vad/pitch_info.h"
 
 namespace webrtc {
 namespace rnn_vad {
 
+// The inverted lags for the pitch interval [|kInitialMinPitch12kHz|,
+// |kMaxPitch12kHz|] are in the range [0, |kNumInvertedLags|].
+static_assert(kMaxPitch12kHz > kInitialMinPitch12kHz, "");
+static_assert(kMaxPitch24kHz > kInitialMinPitch24kHz, "");
+constexpr size_t kNumInvertedLags12kHz = kMaxPitch12kHz - kInitialMinPitch12kHz;
+constexpr size_t kNumInvertedLags24kHz = kMaxPitch24kHz - kInitialMinPitch24kHz;
+constexpr int kAutoCorrelationFftOrder = 9;  // Length-512 FFT.
+
+static_assert(1 << kAutoCorrelationFftOrder >
+                  kNumInvertedLags12kHz + kBufSize12kHz - kMaxPitch12kHz,
+              "");
+
 // Performs 2x decimation without any anti-aliasing filter.
 void Decimate2x(rtc::ArrayView<const float, kBufSize24kHz> src,
                 rtc::ArrayView<float, kBufSize12kHz> dst);
@@ -48,6 +61,25 @@
     rtc::ArrayView<const float, kBufSize24kHz> pitch_buf,
     rtc::ArrayView<float, kMaxPitch24kHz + 1> yy_values);
 
+// Computes the auto-correlation coefficients for a given pitch interval.
+// |auto_corr| indexes are inverted lags.
+//
+// The auto-correlations coefficients are computed as follows:
+// |.........|...........|  <- pitch buffer
+//           [ x (fixed) ]
+// [   y_0   ]
+//         [ y_{m-1} ]
+// x and y are sub-array of equal length; x is never moved, whereas y slides.
+// The cross-correlation between y_0 and x corresponds to the auto-correlation
+// for the maximum pitch period. Hence, the first value in |auto_corr| has an
+// inverted lag equal to 0 that corresponds to a lag equal to the maximum pitch
+// period.
+void ComputePitchAutoCorrelation(
+    rtc::ArrayView<const float, kBufSize12kHz> pitch_buf,
+    size_t max_pitch_period,
+    rtc::ArrayView<float, kNumInvertedLags12kHz> auto_corr,
+    webrtc::RealFourier* fft);
+
 // Given the auto-correlation coefficients stored according to
 // ComputePitchAutoCorrelation() (i.e., using inverted lags), returns the best
 // and the second best pitch periods.
diff --git a/modules/audio_processing/agc2/rnn_vad/pitch_search_internal_unittest.cc b/modules/audio_processing/agc2/rnn_vad/pitch_search_internal_unittest.cc
index bd2ea24..8ff6ac1 100644
--- a/modules/audio_processing/agc2/rnn_vad/pitch_search_internal_unittest.cc
+++ b/modules/audio_processing/agc2/rnn_vad/pitch_search_internal_unittest.cc
@@ -9,6 +9,7 @@
  */
 
 #include "modules/audio_processing/agc2/rnn_vad/pitch_search_internal.h"
+#include "common_audio/real_fourier.h"
 
 #include <array>
 #include <tuple>
@@ -29,6 +30,34 @@
 };
 constexpr std::array<float, 2> kTestPitchGains = {0.35f, 0.75f};
 
+constexpr size_t kNumPitchBufSquareEnergies = 385;
+constexpr size_t kNumPitchBufAutoCorrCoeffs = 147;
+constexpr size_t kTestDataSize =
+    kBufSize24kHz + kNumPitchBufSquareEnergies + kNumPitchBufAutoCorrCoeffs;
+
+class TestData {
+ public:
+  TestData() {
+    auto test_data_reader = CreatePitchSearchTestDataReader();
+    test_data_reader->ReadChunk(test_data_);
+  }
+  rtc::ArrayView<const float, kBufSize24kHz> GetPitchBufView() {
+    return {test_data_.data(), kBufSize24kHz};
+  }
+  rtc::ArrayView<const float, kNumPitchBufSquareEnergies>
+  GetPitchBufSquareEnergiesView() {
+    return {test_data_.data() + kBufSize24kHz, kNumPitchBufSquareEnergies};
+  }
+  rtc::ArrayView<const float, kNumPitchBufAutoCorrCoeffs>
+  GetPitchBufAutoCorrCoeffsView() {
+    return {test_data_.data() + kBufSize24kHz + kNumPitchBufSquareEnergies,
+            kNumPitchBufAutoCorrCoeffs};
+  }
+
+ private:
+  std::array<float, kTestDataSize> test_data_;
+};
+
 }  // namespace
 
 class ComputePitchGainThresholdTest
@@ -78,7 +107,7 @@
         std::make_tuple(78, 2, 156, 0.72750503f, 153, 0.85069299f, 0.618379f)));
 
 TEST(RnnVadTest, ComputeSlidingFrameSquareEnergiesBitExactness) {
-  PitchTestData test_data;
+  TestData test_data;
   std::array<float, kNumPitchBufSquareEnergies> computed_output;
   {
     // TODO(bugs.webrtc.org/8948): Add when the issue is fixed.
@@ -91,8 +120,51 @@
                      computed_output, 3e-2f);
 }
 
+TEST(RnnVadTest, ComputePitchAutoCorrelationBitExactness) {
+  TestData test_data;
+  std::array<float, kBufSize12kHz> pitch_buf_decimated;
+  Decimate2x(test_data.GetPitchBufView(), pitch_buf_decimated);
+  std::array<float, kNumPitchBufAutoCorrCoeffs> computed_output;
+  {
+    // TODO(bugs.webrtc.org/8948): Add when the issue is fixed.
+    // FloatingPointExceptionObserver fpe_observer;
+    std::unique_ptr<RealFourier> fft =
+        RealFourier::Create(kAutoCorrelationFftOrder);
+    ComputePitchAutoCorrelation(pitch_buf_decimated, kMaxPitch12kHz,
+                                computed_output, fft.get());
+  }
+  auto auto_corr_view = test_data.GetPitchBufAutoCorrCoeffsView();
+  ExpectNearAbsolute({auto_corr_view.data(), auto_corr_view.size()},
+                     computed_output, 3e-3f);
+}
+
+// Check that the auto correlation function computes the right thing for a
+// simple use case.
+TEST(RnnVadTest, ComputePitchAutoCorrelationConstantBuffer) {
+  // Create constant signal with no pitch.
+  std::array<float, kBufSize12kHz> pitch_buf_decimated;
+  std::fill(pitch_buf_decimated.begin(), pitch_buf_decimated.end(), 1.f);
+
+  std::array<float, kNumPitchBufAutoCorrCoeffs> computed_output;
+  {
+    // TODO(bugs.webrtc.org/8948): Add when the issue is fixed.
+    // FloatingPointExceptionObserver fpe_observer;
+    std::unique_ptr<RealFourier> fft =
+        RealFourier::Create(kAutoCorrelationFftOrder);
+    ComputePitchAutoCorrelation(pitch_buf_decimated, kMaxPitch12kHz,
+                                computed_output, fft.get());
+  }
+
+  // The expected output is constantly the length of the fixed 'x'
+  // array in ComputePitchAutoCorrelation.
+  std::array<float, kNumPitchBufAutoCorrCoeffs> expected_output;
+  std::fill(expected_output.begin(), expected_output.end(),
+            kBufSize12kHz - kMaxPitch12kHz);
+  ExpectNearAbsolute(expected_output, computed_output, 4e-5f);
+}
+
 TEST(RnnVadTest, FindBestPitchPeriodsBitExactness) {
-  PitchTestData test_data;
+  TestData test_data;
   std::array<float, kBufSize12kHz> pitch_buf_decimated;
   Decimate2x(test_data.GetPitchBufView(), pitch_buf_decimated);
   std::array<size_t, 2> pitch_candidates_inv_lags;
@@ -109,7 +181,7 @@
 }
 
 TEST(RnnVadTest, RefinePitchPeriod48kHzBitExactness) {
-  PitchTestData test_data;
+  TestData test_data;
   std::array<float, kBufSize12kHz> pitch_buf_decimated;
   Decimate2x(test_data.GetPitchBufView(), pitch_buf_decimated);
   size_t pitch_inv_lag;
@@ -135,7 +207,7 @@
   const float prev_pitch_gain = std::get<2>(params);
   const int expected_pitch_period = std::get<3>(params);
   const float expected_pitch_gain = std::get<4>(params);
-  PitchTestData test_data;
+  TestData test_data;
   {
     // TODO(bugs.webrtc.org/8948): Add when the issue is fixed.
     // FloatingPointExceptionObserver fpe_observer;
diff --git a/modules/audio_processing/agc2/rnn_vad/test_utils.cc b/modules/audio_processing/agc2/rnn_vad/test_utils.cc
index 4dae8cd..8decbd0 100644
--- a/modules/audio_processing/agc2/rnn_vad/test_utils.cc
+++ b/modules/audio_processing/agc2/rnn_vad/test_utils.cc
@@ -111,28 +111,6 @@
   return {std::move(ptr), ptr->data_length()};
 }
 
-PitchTestData::PitchTestData() {
-  auto test_data_reader = CreatePitchSearchTestDataReader();
-  test_data_reader->ReadChunk(test_data_);
-}
-
-PitchTestData::~PitchTestData() = default;
-
-rtc::ArrayView<const float, kBufSize24kHz> PitchTestData::GetPitchBufView() {
-  return {test_data_.data(), kBufSize24kHz};
-}
-
-rtc::ArrayView<const float, kNumPitchBufSquareEnergies>
-PitchTestData::GetPitchBufSquareEnergiesView() {
-  return {test_data_.data() + kBufSize24kHz, kNumPitchBufSquareEnergies};
-}
-
-rtc::ArrayView<const float, kNumPitchBufAutoCorrCoeffs>
-PitchTestData::GetPitchBufAutoCorrCoeffsView() {
-  return {test_data_.data() + kBufSize24kHz + kNumPitchBufSquareEnergies,
-          kNumPitchBufAutoCorrCoeffs};
-}
-
 }  // namespace test
 }  // namespace rnn_vad
 }  // namespace webrtc
diff --git a/modules/audio_processing/agc2/rnn_vad/test_utils.h b/modules/audio_processing/agc2/rnn_vad/test_utils.h
index f9d7376..15be85a 100644
--- a/modules/audio_processing/agc2/rnn_vad/test_utils.h
+++ b/modules/audio_processing/agc2/rnn_vad/test_utils.h
@@ -12,7 +12,6 @@
 #define MODULES_AUDIO_PROCESSING_AGC2_RNN_VAD_TEST_UTILS_H_
 
 #include <algorithm>
-#include <array>
 #include <fstream>
 #include <limits>
 #include <memory>
@@ -21,7 +20,6 @@
 #include <vector>
 
 #include "api/array_view.h"
-#include "modules/audio_processing/agc2/rnn_vad/common.h"
 #include "rtc_base/checks.h"
 
 namespace webrtc {
@@ -120,27 +118,6 @@
 std::pair<std::unique_ptr<BinaryFileReader<float>>, const size_t>
 CreateVadProbsReader();
 
-constexpr size_t kNumPitchBufAutoCorrCoeffs = 147;
-constexpr size_t kNumPitchBufSquareEnergies = 385;
-constexpr size_t kPitchTestDataSize =
-    kBufSize24kHz + kNumPitchBufSquareEnergies + kNumPitchBufAutoCorrCoeffs;
-
-// Class to retrieve a test pitch buffer content and the expected output for the
-// analysis steps.
-class PitchTestData {
- public:
-  PitchTestData();
-  ~PitchTestData();
-  rtc::ArrayView<const float, kBufSize24kHz> GetPitchBufView();
-  rtc::ArrayView<const float, kNumPitchBufSquareEnergies>
-  GetPitchBufSquareEnergiesView();
-  rtc::ArrayView<const float, kNumPitchBufAutoCorrCoeffs>
-  GetPitchBufAutoCorrCoeffsView();
-
- private:
-  std::array<float, kPitchTestDataSize> test_data_;
-};
-
 }  // namespace test
 }  // namespace rnn_vad
 }  // namespace webrtc