diff --git a/audio/effect/5.0/Android.bp b/audio/effect/5.0/Android.bp
index d60d94a..78b950e 100644
--- a/audio/effect/5.0/Android.bp
+++ b/audio/effect/5.0/Android.bp
@@ -26,6 +26,7 @@
     interfaces: [
         "android.hardware.audio.common@5.0",
         "android.hidl.base@1.0",
+        "android.hidl.safe_union@1.0",
     ],
     types: [
         "AudioBuffer",
diff --git a/audio/effect/5.0/types.hal b/audio/effect/5.0/types.hal
index 84e1108..4b6c196 100644
--- a/audio/effect/5.0/types.hal
+++ b/audio/effect/5.0/types.hal
@@ -53,6 +53,7 @@
  * | Volume         | 6..8   | 0 none
  * | management     |        | 1 implements volume control
  * |                |        | 2 requires volume indication
+ * |                |        | 3 monitors requested volume
  * |                |        | 4 reserved
  * +----------------+--------+--------------------------------------------------
  * | Device         | 9..11  | 0 none
@@ -136,6 +137,7 @@
     VOLUME_MASK = ((1 << VOLUME_SIZE) -1) << VOLUME_SHIFT,
     VOLUME_CTRL = 1 << VOLUME_SHIFT,
     VOLUME_IND = 2 << VOLUME_SHIFT,
+    VOLUME_MONITOR = 3 << VOLUME_SHIFT,
     VOLUME_NONE = 0 << VOLUME_SHIFT,
 
     // Device indication