diff --git a/audio/effect/4.0/IVirtualizerEffect.hal b/audio/effect/4.0/IVirtualizerEffect.hal
index b98ad3f..52038ca 100644
--- a/audio/effect/4.0/IVirtualizerEffect.hal
+++ b/audio/effect/4.0/IVirtualizerEffect.hal
@@ -47,7 +47,8 @@
     getStrength() generates (Result retval, uint16_t strength);
 
     struct SpeakerAngle {
-        AudioChannelMask mask; // speaker channel mask (1 bit set).
+        /** Speaker channel mask */
+        bitfield<AudioChannelMask> mask;
         // all angles are expressed in degrees and
         // are relative to the listener.
         int16_t azimuth; // 0 is the direction the listener faces
@@ -60,7 +61,7 @@
      * Retrieves virtual speaker angles for the given channel mask on the
      * specified device.
      */
-    getVirtualSpeakerAngles(AudioChannelMask mask, AudioDevice device)
+    getVirtualSpeakerAngles(bitfield<AudioChannelMask> mask, AudioDevice device)
             generates (Result retval, vec<SpeakerAngle> speakerAngles);
 
     /**