diff --git a/webrtc/modules/audio_processing/aec/aec_core.c b/webrtc/modules/audio_processing/aec/aec_core.c
index 432988f0b4..3f3d2c088d 100644
--- a/webrtc/modules/audio_processing/aec/aec_core.c
+++ b/webrtc/modules/audio_processing/aec/aec_core.c
@@ -231,7 +231,7 @@ int WebRtcAec_CreateAec(AecCore** aecInst) {
     return -1;
   }
   aec->delay_estimator = WebRtc_CreateDelayEstimator(
-      aec->delay_estimator_farend, kLookaheadBlocks, kLookaheadBlocks);
+      aec->delay_estimator_farend, kLookaheadBlocks);
   if (aec->delay_estimator == NULL) {
     WebRtcAec_FreeAec(aec);
     aec = NULL;
diff --git a/webrtc/modules/audio_processing/aecm/aecm_core.c b/webrtc/modules/audio_processing/aecm/aecm_core.c
index c1a0910eef..0f34874612 100644
--- a/webrtc/modules/audio_processing/aecm/aecm_core.c
+++ b/webrtc/modules/audio_processing/aecm/aecm_core.c
@@ -260,7 +260,7 @@ int WebRtcAecm_CreateCore(AecmCore_t **aecmInst)
       return -1;
     }
     aecm->delay_estimator =
-        WebRtc_CreateDelayEstimator(aecm->delay_estimator_farend, 0, 0);
+        WebRtc_CreateDelayEstimator(aecm->delay_estimator_farend, 0);
     if (aecm->delay_estimator == NULL) {
       WebRtcAecm_FreeCore(aecm);
       aecm = NULL;
diff --git a/webrtc/modules/audio_processing/utility/delay_estimator.c b/webrtc/modules/audio_processing/utility/delay_estimator.c
index c8d9ba841e..3b2043267f 100644
--- a/webrtc/modules/audio_processing/utility/delay_estimator.c
+++ b/webrtc/modules/audio_processing/utility/delay_estimator.c
@@ -308,31 +308,33 @@ void WebRtc_SoftResetBinaryDelayEstimatorFarend(
     BinaryDelayEstimatorFarend* self, int delay_shift) {
   int abs_shift = abs(delay_shift);
   int shift_size = 0;
-  assert(self != NULL);
+  int dest_index = 0;
+  int src_index = 0;
+  int padding_index = 0;
 
+  assert(self != NULL);
   shift_size = self->history_size - abs_shift;
-  if (delay_shift > 0) {
-    memmove(&self->binary_far_history[abs_shift],
-            self->binary_far_history,
-            sizeof(*self->binary_far_history) * shift_size);
-    memmove(&self->far_bit_counts[abs_shift],
-            self->far_bit_counts,
-            sizeof(*self->far_bit_counts) * shift_size);
-    memset(self->binary_far_history, 0,
-           sizeof(*self->binary_far_history) * abs_shift);
-    memset(self->far_bit_counts, 0, sizeof(*self->far_bit_counts) * abs_shift);
+  assert(shift_size > 0);
+  if (delay_shift == 0) {
+    return;
+  } else if (delay_shift > 0) {
+    dest_index = abs_shift;
   } else if (delay_shift < 0) {
-    memmove(self->binary_far_history,
-            &self->binary_far_history[abs_shift],
-            sizeof(*self->binary_far_history) * shift_size);
-    memmove(self->far_bit_counts,
-            &self->far_bit_counts[abs_shift],
-            sizeof(*self->far_bit_counts) * shift_size);
-    memset(&self->binary_far_history[shift_size], 0,
-           sizeof(*self->binary_far_history) * abs_shift);
-    memset(&self->far_bit_counts[shift_size], 0,
-           sizeof(*self->far_bit_counts) * abs_shift);
+    src_index = abs_shift;
+    padding_index = shift_size;
   }
+
+  // Shift and zero pad buffers.
+  memmove(&self->binary_far_history[dest_index],
+          &self->binary_far_history[src_index],
+          sizeof(*self->binary_far_history) * shift_size);
+  memset(&self->binary_far_history[padding_index], 0,
+         sizeof(*self->binary_far_history) * abs_shift);
+  memmove(&self->far_bit_counts[dest_index],
+          &self->far_bit_counts[src_index],
+          sizeof(*self->far_bit_counts) * shift_size);
+  memset(&self->far_bit_counts[padding_index], 0,
+         sizeof(*self->far_bit_counts) * abs_shift);
 }
 
 void WebRtc_AddBinaryFarSpectrum(BinaryDelayEstimatorFarend* handle,
@@ -376,10 +378,10 @@ void WebRtc_FreeBinaryDelayEstimator(BinaryDelayEstimator* self) {
 }
 
 BinaryDelayEstimator* WebRtc_CreateBinaryDelayEstimator(
-    BinaryDelayEstimatorFarend* farend, int max_lookahead, int lookahead) {
+    BinaryDelayEstimatorFarend* farend, int max_lookahead) {
   BinaryDelayEstimator* self = NULL;
 
-  if ((farend != NULL) && (lookahead >= 0) && (max_lookahead >= lookahead)) {
+  if ((farend != NULL) && (max_lookahead >= 0)) {
     // Sanity conditions fulfilled.
     self = malloc(sizeof(BinaryDelayEstimator));
   }
@@ -392,7 +394,7 @@ BinaryDelayEstimator* WebRtc_CreateBinaryDelayEstimator(
     self->robust_validation_enabled = 0;  // Disabled by default.
     self->allowed_offset = 0;
 
-    self->lookahead = lookahead;
+    self->lookahead = max_lookahead;
 
     // Allocate memory for spectrum buffers.  The extra array element in
     // |mean_bit_counts| and |histogram| is a dummy element only used while
@@ -405,7 +407,7 @@ BinaryDelayEstimator* WebRtc_CreateBinaryDelayEstimator(
     malloc_fail |= (self->bit_counts == NULL);
 
     // Allocate memory for history buffers.
-    self->binary_near_history = malloc((lookahead + 1) * sizeof(uint32_t));
+    self->binary_near_history = malloc((max_lookahead + 1) * sizeof(uint32_t));
     malloc_fail |= (self->binary_near_history == NULL);
 
     self->histogram = malloc((farend->history_size + 1) * sizeof(float));
diff --git a/webrtc/modules/audio_processing/utility/delay_estimator.h b/webrtc/modules/audio_processing/utility/delay_estimator.h
index 6574f30824..3d5ffce20e 100644
--- a/webrtc/modules/audio_processing/utility/delay_estimator.h
+++ b/webrtc/modules/audio_processing/utility/delay_estimator.h
@@ -136,42 +136,10 @@ void WebRtc_FreeBinaryDelayEstimator(BinaryDelayEstimator* self);
 // Allocates the memory needed by the binary delay estimation. The memory needs
 // to be initialized separately through WebRtc_InitBinaryDelayEstimator(...).
 //
-// Inputs:
-//      - farend        : Pointer to the far-end part of the Binary Delay
-//                        Estimator. This memory has to be created separately
-//                        prior to this call using
-//                        WebRtc_CreateBinaryDelayEstimatorFarend().
-//
-//                        Note that BinaryDelayEstimator does not take
-//                        ownership of |farend|.
-//
-//      - lookahead     : Amount of non-causal lookahead to use. This can
-//                        detect cases in which a near-end signal occurs before
-//                        the corresponding far-end signal. It will delay the
-//                        estimate for the current block by an equal amount,
-//                        and the returned values will be offset by it.
-//
-//                        A value of zero is the typical no-lookahead case.
-//                        This also represents the minimum delay which can be
-//                        estimated.
-//
-//                        Note that the effective range of delay estimates is
-//                        [-|lookahead|,... ,|history_size|-|lookahead|)
-//                        where |history_size| was set upon creating the far-end
-//                        history buffer size.
-//
-//      - max_lookahead : Maximum amount of non-causal lookahead allowed. This
-//                        is to allow for dynamically changing the lookahead on
-//                        the fly.
-//
-// Return value:
-//      - BinaryDelayEstimator*
-//                      : Created |handle|. If the memory can't be allocated
-//                        or if any of the input parameters are invalid NULL
-//                        is returned.
-//
+// See WebRtc_CreateDelayEstimator(..) in delay_estimator_wrapper.c for detailed
+// description.
 BinaryDelayEstimator* WebRtc_CreateBinaryDelayEstimator(
-    BinaryDelayEstimatorFarend* farend, int max_lookahead, int lookahead);
+    BinaryDelayEstimatorFarend* farend, int max_lookahead);
 
 // Initializes the delay estimation instance created with
 // WebRtc_CreateBinaryDelayEstimator(...).
@@ -230,7 +198,7 @@ int WebRtc_binary_last_delay(BinaryDelayEstimator* self);
 
 // Returns the estimation quality of the last calculated delay updated by the
 // function WebRtc_ProcessBinarySpectrum(...). The estimation quality is a value
-// in the interval [0, 1].  The higher the value, the better quality.
+// in the interval [0, 1].  The higher the value, the better the quality.
 //
 // Return value:
 //    - delay_quality         :  >= 0 - Estimation quality of last calculated
diff --git a/webrtc/modules/audio_processing/utility/delay_estimator_unittest.cc b/webrtc/modules/audio_processing/utility/delay_estimator_unittest.cc
index ff0bbeb122..ca0901d6db 100644
--- a/webrtc/modules/audio_processing/utility/delay_estimator_unittest.cc
+++ b/webrtc/modules/audio_processing/utility/delay_estimator_unittest.cc
@@ -86,14 +86,13 @@ void DelayEstimatorTest::SetUp() {
                                                      kMaxDelay + kLookahead);
   ASSERT_TRUE(farend_handle_ != NULL);
   farend_self_ = reinterpret_cast<DelayEstimatorFarend*>(farend_handle_);
-  handle_ = WebRtc_CreateDelayEstimator(farend_handle_, kLookahead, kLookahead);
+  handle_ = WebRtc_CreateDelayEstimator(farend_handle_, kLookahead);
   ASSERT_TRUE(handle_ != NULL);
   self_ = reinterpret_cast<DelayEstimator*>(handle_);
   binary_farend_ = WebRtc_CreateBinaryDelayEstimatorFarend(kMaxDelay +
                                                            kLookahead);
   ASSERT_TRUE(binary_farend_ != NULL);
-  binary_ = WebRtc_CreateBinaryDelayEstimator(binary_farend_, kLookahead,
-                                              kLookahead);
+  binary_ = WebRtc_CreateBinaryDelayEstimator(binary_farend_, kLookahead);
   ASSERT_TRUE(binary_ != NULL);
 }
 
@@ -202,7 +201,6 @@ void DelayEstimatorTest::RunBinarySpectraTest(int near_offset,
                                               int robust_validation) {
   BinaryDelayEstimator* binary2 =
       WebRtc_CreateBinaryDelayEstimator(binary_farend_,
-                                        kLookahead + lookahead_offset,
                                         kLookahead + lookahead_offset);
   // Verify the delay for both causal and non-causal systems. For causal systems
   // the delay is equivalent with a positive |offset| of the far-end sequence.
@@ -234,12 +232,9 @@ TEST_F(DelayEstimatorTest, CorrectErrorReturnsOfWrapper) {
   EXPECT_TRUE(handle == NULL);
 
   handle = handle_;
-  handle = WebRtc_CreateDelayEstimator(NULL, kLookahead, kLookahead);
+  handle = WebRtc_CreateDelayEstimator(NULL, kLookahead);
   EXPECT_TRUE(handle == NULL);
-  handle = WebRtc_CreateDelayEstimator(farend_handle_, kLookahead, -1);
-  EXPECT_TRUE(handle == NULL);
-  handle = WebRtc_CreateDelayEstimator(farend_handle_, kLookahead - 1,
-                                       kLookahead);
+  handle = WebRtc_CreateDelayEstimator(farend_handle_, -1);
   EXPECT_TRUE(handle == NULL);
 
   // WebRtc_InitDelayEstimatorFarend() and WebRtc_InitDelayEstimator() should
@@ -445,14 +440,9 @@ TEST_F(DelayEstimatorTest, CorrectErrorReturnsOfBinaryEstimator) {
   // |binary_handle| should be NULL.
   // Make sure we have a non-NULL value at start, so we can detect NULL after
   // create failure.
-  binary_handle = WebRtc_CreateBinaryDelayEstimator(NULL, kLookahead,
-                                                    kLookahead);
+  binary_handle = WebRtc_CreateBinaryDelayEstimator(NULL, kLookahead);
   EXPECT_TRUE(binary_handle == NULL);
-  binary_handle = WebRtc_CreateBinaryDelayEstimator(binary_farend_, kLookahead,
-                                                    -1);
-  EXPECT_TRUE(binary_handle == NULL);
-  binary_handle = WebRtc_CreateBinaryDelayEstimator(binary_farend_,
-                                                    kLookahead - 1, kLookahead);
+  binary_handle = WebRtc_CreateBinaryDelayEstimator(binary_farend_, -1);
   EXPECT_TRUE(binary_handle == NULL);
 }
 
@@ -539,8 +529,7 @@ TEST_F(DelayEstimatorTest, VerifyLookaheadAtCreate) {
   void* farend_handle = WebRtc_CreateDelayEstimatorFarend(kSpectrumSize,
                                                           kMaxDelay);
   ASSERT_TRUE(farend_handle != NULL);
-  void* handle = WebRtc_CreateDelayEstimator(farend_handle, kLookahead,
-                                             kLookahead);
+  void* handle = WebRtc_CreateDelayEstimator(farend_handle, kLookahead);
   ASSERT_TRUE(handle != NULL);
   EXPECT_EQ(kLookahead, WebRtc_lookahead(handle));
   WebRtc_FreeDelayEstimator(handle);
diff --git a/webrtc/modules/audio_processing/utility/delay_estimator_wrapper.c b/webrtc/modules/audio_processing/utility/delay_estimator_wrapper.c
index 212e740dd7..6ec894e65e 100644
--- a/webrtc/modules/audio_processing/utility/delay_estimator_wrapper.c
+++ b/webrtc/modules/audio_processing/utility/delay_estimator_wrapper.c
@@ -267,8 +267,7 @@ void WebRtc_FreeDelayEstimator(void* handle) {
   free(self);
 }
 
-void* WebRtc_CreateDelayEstimator(void* farend_handle, int max_lookahead,
-                                  int lookahead) {
+void* WebRtc_CreateDelayEstimator(void* farend_handle, int max_lookahead) {
   DelayEstimator* self = NULL;
   DelayEstimatorFarend* farend = (DelayEstimatorFarend*) farend_handle;
 
@@ -281,8 +280,7 @@ void* WebRtc_CreateDelayEstimator(void* farend_handle, int max_lookahead,
 
     // Allocate memory for the farend spectrum handling.
     self->binary_handle =
-        WebRtc_CreateBinaryDelayEstimator(farend->binary_farend, max_lookahead,
-                                          lookahead);
+        WebRtc_CreateBinaryDelayEstimator(farend->binary_farend, max_lookahead);
     memory_fail |= (self->binary_handle == NULL);
 
     // Allocate memory for spectrum buffers.
@@ -326,9 +324,22 @@ int WebRtc_SoftResetDelayEstimator(void* handle, int delay_shift) {
   return WebRtc_SoftResetBinaryDelayEstimator(self->binary_handle, delay_shift);
 }
 
+int WebRtc_set_lookahead(void* handle, int lookahead) {
+  DelayEstimator* self = (DelayEstimator*) handle;
+  assert(self != NULL);
+  assert(self->binary_handle != NULL);
+  if ((lookahead > self->binary_handle->near_history_size - 1) ||
+      (lookahead < 0)) {
+    return -1;
+  }
+  self->binary_handle->lookahead = lookahead;
+  return self->binary_handle->lookahead;
+}
+
 int WebRtc_lookahead(void* handle) {
   DelayEstimator* self = (DelayEstimator*) handle;
   assert(self != NULL);
+  assert(self->binary_handle != NULL);
   return self->binary_handle->lookahead;
 }
 
@@ -360,6 +371,7 @@ int WebRtc_enable_robust_validation(void* handle, int enable) {
   if ((enable < 0) || (enable > 1)) {
     return -1;
   }
+  assert(self->binary_handle != NULL);
   self->binary_handle->robust_validation_enabled = enable;
   return 0;
 }
diff --git a/webrtc/modules/audio_processing/utility/delay_estimator_wrapper.h b/webrtc/modules/audio_processing/utility/delay_estimator_wrapper.h
index 3de43f3fb5..13e86bdd43 100644
--- a/webrtc/modules/audio_processing/utility/delay_estimator_wrapper.h
+++ b/webrtc/modules/audio_processing/utility/delay_estimator_wrapper.h
@@ -98,11 +98,18 @@ void WebRtc_FreeDelayEstimator(void* handle);
 //                        ownership of |farend_handle|, which has to be torn
 //                        down properly after this instance.
 //
-//      - lookahead     : Amount of non-causal lookahead to use. This can
-//                        detect cases in which a near-end signal occurs before
-//                        the corresponding far-end signal. It will delay the
-//                        estimate for the current block by an equal amount,
-//                        and the returned values will be offset by it.
+//      - max_lookahead : Maximum amount of non-causal lookahead allowed. The
+//                        actual amount of lookahead used can be controlled by
+//                        WebRtc_set_lookahead(...). The default |lookahead| is
+//                        set to |max_lookahead| at create time. Use
+//                        WebRtc_set_lookahead(...) before start if a different
+//                        value is desired.
+//
+//                        Using lookahead can detect cases in which a near-end
+//                        signal occurs before the corresponding far-end signal.
+//                        It will delay the estimate for the current block by an
+//                        equal amount, and the returned values will be offset
+//                        by it.
 //
 //                        A value of zero is the typical no-lookahead case.
 //                        This also represents the minimum delay which can be
@@ -113,17 +120,12 @@ void WebRtc_FreeDelayEstimator(void* handle);
 //                        where |history_size| was set upon creating the far-end
 //                        history buffer size.
 //
-//      - max_lookahead : Maximum amount of non-causal lookahead allowed. This
-//                        is to allow for dynamically changing the lookahead on
-//                        the fly.
-//
 // Return value:
 //      - void*         : Created |handle|. If the memory can't be allocated or
 //                        if any of the input parameters are invalid NULL is
 //                        returned.
 //
-void* WebRtc_CreateDelayEstimator(void* farend_handle, int max_lookahead,
-                                  int lookahead);
+void* WebRtc_CreateDelayEstimator(void* farend_handle, int max_lookahead);
 
 // Initializes the delay estimation instance returned by
 // WebRtc_CreateDelayEstimator(...)
@@ -145,6 +147,18 @@ int WebRtc_InitDelayEstimator(void* handle);
 //
 int WebRtc_SoftResetDelayEstimator(void* handle, int delay_shift);
 
+// Sets the amount of |lookahead| to use. Valid values are [0, max_lookahead]
+// where |max_lookahead| was set at create time through
+// WebRtc_CreateDelayEstimator(...).
+//
+// Input:
+//      - lookahead     : The amount of blocks to shift history buffers.
+//
+// Return value:
+//      - new_lookahead : The actual number of shifts performed.
+//
+int WebRtc_set_lookahead(void* handle, int lookahead);
+
 // Returns the amount of lookahead we currently use.
 int WebRtc_lookahead(void* handle);
 
@@ -222,7 +236,7 @@ int WebRtc_last_delay(void* handle);
 // Returns the estimation quality/probability of the last calculated delay
 // updated by the function WebRtc_DelayEstimatorProcess(...). The estimation
 // quality is a value in the interval [0, 1]. The higher the value, the better
-// quality.
+// the quality.
 //
 // Return value:
 //      - delay_quality : >= 0  - Estimation quality of last calculated delay.