diff --git a/include/system/audio.h b/include/system/audio.h
index 1c70240..0eb28b0 100644
--- a/include/system/audio.h
+++ b/include/system/audio.h
@@ -585,6 +585,8 @@
     AUDIO_DEVICE_OUT_FM                        = 0x100000,
     /* Line out for av devices */
     AUDIO_DEVICE_OUT_AUX_LINE                  = 0x200000,
+    /* limited-output speaker device for acoustic safety */
+    AUDIO_DEVICE_OUT_SPEAKER_SAFE              = 0x400000,
     AUDIO_DEVICE_OUT_DEFAULT                   = AUDIO_DEVICE_BIT_DEFAULT,
     AUDIO_DEVICE_OUT_ALL      = (AUDIO_DEVICE_OUT_EARPIECE |
                                  AUDIO_DEVICE_OUT_SPEAKER |
@@ -608,6 +610,7 @@
                                  AUDIO_DEVICE_OUT_SPDIF |
                                  AUDIO_DEVICE_OUT_FM |
                                  AUDIO_DEVICE_OUT_AUX_LINE |
+                                 AUDIO_DEVICE_OUT_SPEAKER_SAFE |
                                  AUDIO_DEVICE_OUT_DEFAULT),
     AUDIO_DEVICE_OUT_ALL_A2DP = (AUDIO_DEVICE_OUT_BLUETOOTH_A2DP |
                                  AUDIO_DEVICE_OUT_BLUETOOTH_A2DP_HEADPHONES |