diff --git a/hal/audio_extn/sound_trigger_prop_intf.h b/hal/audio_extn/sound_trigger_prop_intf.h
new file mode 100644
index 0000000..90a9aa9
--- /dev/null
+++ b/hal/audio_extn/sound_trigger_prop_intf.h
@@ -0,0 +1,61 @@
+/*
+ * Extrapolated / reversed header for Sound Trigger
+ */
+
+#ifndef SOUND_TRIGGER_PROP_INTF_H
+#define SOUND_TRIGGER_PROP_INTF_H
+
+struct sound_trigger_session_info {
+    int capture_handle;
+    struct pcm *pcm;
+    struct pcm_config config;
+};
+
+enum audio_event_type {
+    AUDIO_EVENT_CAPTURE_DEVICE_INACTIVE,
+    AUDIO_EVENT_CAPTURE_DEVICE_ACTIVE,
+    dummy1,
+    dummy2,
+    AUDIO_EVENT_STOP_LAB,
+    AUDIO_EVENT_SSR,
+    AUDIO_EVENT_NUM_ST_SESSIONS,
+    AUDIO_EVENT_READ_SAMPLES,
+};
+
+enum sound_trigger_event_type {
+    ST_EVENT_SESSION_REGISTER,
+    ST_EVENT_SESSION_DEREGISTER
+};
+typedef enum sound_trigger_event_type sound_trigger_event_type_t;
+
+enum ssr_event_status {
+    SND_CARD_STATUS_OFFLINE,
+    SND_CARD_STATUS_ONLINE,
+    CPE_STATUS_OFFLINE,
+    CPE_STATUS_ONLINE
+};
+
+struct sound_trigger_event_info {
+    struct sound_trigger_session_info st_ses;
+};
+typedef struct sound_trigger_event_info sound_trigger_event_info_t;
+
+struct audio_read_samples_info {
+    struct sound_trigger_session_info *ses_info;
+    void *buf;
+    size_t num_bytes;
+};
+
+struct audio_event_info {
+    union {
+        enum ssr_event_status status;
+        int value;
+        struct sound_trigger_session_info ses_info;
+        struct audio_read_samples_info aud_info;
+    }u;
+};
+typedef struct audio_event_info audio_event_info_t;
+
+typedef int (*sound_trigger_hw_call_back_t)(enum audio_event_type,
+                                            struct audio_event_info*);
+#endif