diff --git a/doc/handsfree-api.txt b/doc/handsfree-api.txt
index 0b5d4215..d6ffca57 100644
--- a/doc/handsfree-api.txt
+++ b/doc/handsfree-api.txt
@@ -44,6 +44,7 @@ Properties	array{string} Features [readonly]
 			supported values are:
 				"voice-recognition"
 				"attach-voice-tag"
+				"echo-canceling-and-noise-reduction"
 
 		boolean InbandRinging [readonly]
 
@@ -56,6 +57,15 @@ Properties	array{string} Features [readonly]
 			to activate or deactivate the function from the HF, or
 			the AG could autonomously initiate it.
 
+		boolean EchoCancelingNoiseReduction [readwrite]
+
+			Non-persistent Boolean property representing whether
+			echo canceling and noise reduction is enabled in the
+			AG. This feature can only be disabled once from the
+			HF unit; the current specification does not allow the
+			HF unit from enabling this feature on the AG once
+			it has been disabled.
+
 		byte BatteryChargeLevel [readonly]
 
 			The current charge level of the battery.  The value