diff --git a/asset_dev/sfx/wall_switch.aup3 b/asset_dev/sfx/wall_switch.aup3
new file mode 100644
index 0000000..ba8384c
Binary files /dev/null and b/asset_dev/sfx/wall_switch.aup3 differ
diff --git a/assets/sfx/grunk/heartbeat.wav b/assets/sfx/grunk/heartbeat.wav
new file mode 100644
index 0000000..f7eb831
Binary files /dev/null and b/assets/sfx/grunk/heartbeat.wav differ
diff --git a/assets/sfx/grunk/heartbeat.wav.import b/assets/sfx/grunk/heartbeat.wav.import
new file mode 100644
index 0000000..9c46e52
--- /dev/null
+++ b/assets/sfx/grunk/heartbeat.wav.import
@@ -0,0 +1,24 @@
+[remap]
+
+importer="wav"
+type="AudioStreamWAV"
+uid="uid://0usonf3pjh3o"
+path="res://.godot/imported/heartbeat.wav-23e070ceda3a2c6b2886e8fd85673555.sample"
+
+[deps]
+
+source_file="res://assets/sfx/grunk/heartbeat.wav"
+dest_files=["res://.godot/imported/heartbeat.wav-23e070ceda3a2c6b2886e8fd85673555.sample"]
+
+[params]
+
+force/8_bit=false
+force/mono=false
+force/max_rate=false
+force/max_rate_hz=44100
+edit/trim=false
+edit/normalize=false
+edit/loop_mode=0
+edit/loop_begin=0
+edit/loop_end=-1
+compress/mode=2
diff --git a/src/world/mechanics/heart/gunk_heart.tscn b/src/world/mechanics/heart/gunk_heart.tscn
index 7a41b17..53e3837 100644
--- a/src/world/mechanics/heart/gunk_heart.tscn
+++ b/src/world/mechanics/heart/gunk_heart.tscn
@@ -1,7 +1,8 @@
-[gd_scene load_steps=10 format=4 uid="uid://d0j20q65wnqsr"]
+[gd_scene load_steps=11 format=4 uid="uid://d0j20q65wnqsr"]
 
 [ext_resource type="Script" uid="uid://d2k75cyykkk0s" path="res://src/world/mechanics/heart/gunk_heart.gd" id="1_ftym0"]
 [ext_resource type="Script" uid="uid://bukihqt1lybnx" path="res://src/util/frame_skipper.gd" id="2_xgyvt"]
+[ext_resource type="AudioStream" uid="uid://0usonf3pjh3o" path="res://assets/sfx/grunk/heartbeat.wav" id="3_eu6st"]
 
 [sub_resource type="StandardMaterial3D" id="StandardMaterial3D_xgyvt"]
 albedo_color = Color(0, 0.0313726, 0.101961, 1)
@@ -69,6 +70,18 @@ tracks/1/keys = {
 "update": 0,
 "values": [0.0]
 }
+tracks/2/type = "value"
+tracks/2/imported = false
+tracks/2/enabled = true
+tracks/2/path = NodePath("HeartbeatSFX:playing")
+tracks/2/interp = 1
+tracks/2/loop_wrap = true
+tracks/2/keys = {
+"times": PackedFloat32Array(0),
+"transitions": PackedFloat32Array(1),
+"update": 1,
+"values": [false]
+}
 
 [sub_resource type="Animation" id="Animation_eu6st"]
 resource_name = "pulse"
@@ -97,6 +110,18 @@ tracks/1/keys = {
 "update": 0,
 "values": [0.0, 2.0, 0.0]
 }
+tracks/2/type = "value"
+tracks/2/imported = false
+tracks/2/enabled = true
+tracks/2/path = NodePath("HeartbeatSFX:playing")
+tracks/2/interp = 1
+tracks/2/loop_wrap = true
+tracks/2/keys = {
+"times": PackedFloat32Array(0),
+"transitions": PackedFloat32Array(1),
+"update": 1,
+"values": [true]
+}
 
 [sub_resource type="AnimationLibrary" id="AnimationLibrary_kv3oi"]
 _data = {
@@ -134,4 +159,9 @@ libraries = {
 }
 speed_scale = 4.0
 
+[node name="HeartbeatSFX" type="AudioStreamPlayer3D" parent="."]
+stream = ExtResource("3_eu6st")
+unit_size = 0.4
+bus = &"SFX"
+
 [connection signal="timeout" from="PulseTimer" to="." method="pulse"]
diff --git a/vault/TODO.md b/vault/TODO.md
index 4a76d1d..0d118d5 100644
--- a/vault/TODO.md
+++ b/vault/TODO.md
@@ -61,8 +61,9 @@
 		- [x] switch activation
 		- [x] bulkhead opening
 		- [x] grunk alarm shriek
-		- [ ] grunk relay chitter
-		- [ ] grunk chittering
+		- [ ] grunk relay pulse
+		- [x] grunk heartbeat
+		- [x] grunk chittering
 		- [ ] grunkbeast???
 		- [x] grunk ambiance
 		- [x] spaceship ambiance
diff --git a/vault/assets/asset credits.md b/vault/assets/asset credits.md
index 90b16ac..b867000 100644
--- a/vault/assets/asset credits.md	
+++ b/vault/assets/asset credits.md	
@@ -81,4 +81,16 @@
 		- CC0
 		- retrieved from https://freesound.org/people/A_Kuha/sounds/676412/
 		- assets/sfx/wall_switch.wav
+		- modified
+	- "pulse tone echo" pack
+		- author: martian
+		- CC0
+		- retrieved from https://freesound.org/people/martian/packs/1173/
+		- assets/sfx/grunk/greeble*.wav
+		- modified
+	- "HeartBeatNEW.aif"
+		- author: Woodingp
+		- CC0
+		- retrieved from https://freesound.org/people/Woodingp/sounds/116642/
+		- assets/sfx/grunk/heartbeat.wav
 		- modified
\ No newline at end of file