diff --git a/include/media/AudioSystem.h b/include/media/AudioSystem.h
index 1081c35..cce2400 100644
--- a/include/media/AudioSystem.h
+++ b/include/media/AudioSystem.h
@@ -472,7 +472,7 @@
     AudioParameter(const String8& keyValuePairs);
     virtual ~AudioParameter();
 
-    // reserved parameter keys for changeing standard parameters with setParameters() function.
+    // reserved parameter keys for changing standard parameters with setParameters() function.
     // Using these keys is mandatory for AudioFlinger to properly monitor audio output/input
     // configuration changes and act accordingly.
     //  keyRouting: to change audio routing, value is an int in AudioSystem::audio_devices
@@ -480,11 +480,14 @@
     //  keyFormat: to change audio format, value is an int in AudioSystem::audio_format
     //  keyChannels: to change audio channel configuration, value is an int in AudioSystem::audio_channels
     //  keyFrameCount: to change audio output frame count, value is an int
+    //  keyInputSource: to change audio input source, value is an int in audio_source
+    //     (defined in media/mediarecorder.h)
     static const char *keyRouting;
     static const char *keySamplingRate;
     static const char *keyFormat;
     static const char *keyChannels;
     static const char *keyFrameCount;
+    static const char *keyInputSource;
 
     String8 toString();