diff --git a/SDAVAssetExportSession.h b/SDAVAssetExportSession.h
index b954132..33aec49 100644
--- a/SDAVAssetExportSession.h
+++ b/SDAVAssetExportSession.h
@@ -37,10 +37,15 @@
 
 @property (nonatomic, weak) id<SDAVAssetExportSessionDelegate> delegate;
 
+@property (nonatomic, strong, readonly) AVAssetReader *reader;
+@property (nonatomic, strong, readonly) AVAssetWriter *writer;
+@property (nonatomic, strong, readonly) dispatch_queue_t inputQueue;
+
 /**
  * The asset with which the export session was initialized.
  */
-@property (nonatomic, strong, readonly) AVAsset *asset;
+@property (nonatomic, strong) AVAsset *asset;
+@property (nonatomic, copy) AVAudioTimePitchAlgorithm audioTimePitchAlgorithm NS_AVAILABLE(10_9, 7_0);
 
 /**
  * Indicates whether video composition is enabled for export, and supplies the instructions for video composition.
@@ -123,7 +128,7 @@
  *
  * If there is no error to report, the value of this property is nil.
  */
-@property (nonatomic, strong, readonly) NSError *error;
+@property (nonatomic, strong) NSError *error;
 
 /**
  * The progress of the export on a scale from 0 to 1.
diff --git a/SDAVAssetExportSession.m b/SDAVAssetExportSession.m
index e99993b..61f99c3 100755
--- a/SDAVAssetExportSession.m
+++ b/SDAVAssetExportSession.m
@@ -16,14 +16,13 @@
 @interface SDAVAssetExportSession ()
 
 @property (nonatomic, assign, readwrite) float progress;
-
-@property (nonatomic, strong) AVAssetReader *reader;
 @property (nonatomic, strong) AVAssetReaderVideoCompositionOutput *videoOutput;
 @property (nonatomic, strong) AVAssetReaderAudioMixOutput *audioOutput;
-@property (nonatomic, strong) AVAssetWriter *writer;
 @property (nonatomic, strong) AVAssetWriterInput *videoInput;
 @property (nonatomic, strong) AVAssetWriterInputPixelBufferAdaptor *videoPixelBufferAdaptor;
 @property (nonatomic, strong) AVAssetWriterInput *audioInput;
+@property (nonatomic, strong) AVAssetReader *reader;
+@property (nonatomic, strong) AVAssetWriter *writer;
 @property (nonatomic, strong) dispatch_queue_t inputQueue;
 @property (nonatomic, strong) void (^completionHandler)(void);
 
@@ -145,13 +144,16 @@ - (void)exportAsynchronouslyWithCompletionHandler:(void (^)(void))handler
     //
     NSArray *audioTracks = [self.asset tracksWithMediaType:AVMediaTypeAudio];
     if (audioTracks.count > 0) {
-      self.audioOutput = [AVAssetReaderAudioMixOutput assetReaderAudioMixOutputWithAudioTracks:audioTracks audioSettings:nil];
-      self.audioOutput.alwaysCopiesSampleData = NO;
-      self.audioOutput.audioMix = self.audioMix;
-      if ([self.reader canAddOutput:self.audioOutput])
-      {
-          [self.reader addOutput:self.audioOutput];
-      }
+        self.audioOutput = [AVAssetReaderAudioMixOutput assetReaderAudioMixOutputWithAudioTracks:audioTracks audioSettings:nil];
+        if (self.audioTimePitchAlgorithm) {
+            self.audioOutput.audioTimePitchAlgorithm = self.audioTimePitchAlgorithm;
+        }
+        self.audioOutput.alwaysCopiesSampleData = NO;
+        self.audioOutput.audioMix = self.audioMix;
+        if ([self.reader canAddOutput:self.audioOutput])
+        {
+            [self.reader addOutput:self.audioOutput];
+        }
     } else {
         // Just in case this gets reused
         self.audioOutput = nil;