diff --git a/webrtc/modules/audio_processing/audio_buffer.h b/webrtc/modules/audio_processing/audio_buffer.h
index 2fab814a0..db24e959f 100644
--- a/webrtc/modules/audio_processing/audio_buffer.h
+++ b/webrtc/modules/audio_processing/audio_buffer.h
@@ -56,6 +56,7 @@ class AudioBuffer {
   int samples_per_split_channel() const;
   int samples_per_keyboard_channel() const;
 
+  // It can be assumed that channels are stored contiguously.
   int16_t* data(int channel);
   const int16_t* data(int channel) const;
   int16_t* low_pass_split_data(int channel);