SSoverlays for human icons, mostly works

Closer to working 100%

But legitimately /tg/ icons

Move lighting to it's own plane, fix observers

Fix humans layering over other objects incorrectly

Nyaaaaa~

code/modules/surgery/organs/ears.dm

@@ -0,0 +1,76 @@
+/obj/item/organ/internal/ears
+	name = "ears"
+	icon_state = "ears"
+	gender = PLURAL
+	organ_tag = "ears"
+	parent_organ = "head"
+	slot = "ears"
+
+	// `deaf` measures "ticks" of deafness. While > 0, the person is deaf.
+	var/deaf = 0
+
+	// `ear_damage` measures long term damage to the ears, if too high,
+	// the person will not have either `deaf` or `ear_damage` decrease
+	// without external aid (earmuffs, drugs)
+	var/ear_damage = 0
+
+/obj/item/organ/internal/ears/on_life()
+	if(!iscarbon(owner))
+		return
+	var/mob/living/carbon/C = owner
+	// genetic deafness prevents the body from using the ears, even if healthy
+	if(C.disabilities & DEAF)
+		deaf = max(deaf, 1)
+	else
+		if(ishuman(C))
+			var/mob/living/carbon/human/H = C
+			if((H.l_ear && H.l_ear.flags_2 & HEALS_EARS_2) || (H.r_ear && H.r_ear.flags_2 & HEALS_EARS_2))
+				deaf = max(deaf - 1, 1)
+				ear_damage = max(ear_damage - 0.10, 0)
+		// if higher than UNHEALING_EAR_DAMAGE, no natural healing occurs.
+		if(ear_damage < UNHEALING_EAR_DAMAGE)
+			ear_damage = max(ear_damage - 0.05, 0)
+			deaf = max(deaf - 1, 0)
+
+/obj/item/organ/internal/ears/proc/RestoreEars()
+	deaf = 0
+	ear_damage = 0
+	
+	var/mob/living/carbon/C = owner
+	if(istype(C) && C.disabilities & DEAF)
+		deaf = 1
+
+/obj/item/organ/internal/ears/proc/AdjustEarDamage(ddmg, ddeaf)
+	ear_damage = max(ear_damage + ddmg, 0)
+	deaf = max(deaf + ddeaf, 0)
+
+/obj/item/organ/internal/ears/proc/MinimumDeafTicks(value)
+	deaf = max(deaf, value)
+
+// Mob procs
+/mob/living/carbon/RestoreEars()
+	var/obj/item/organ/internal/ears/ears = get_int_organ(/obj/item/organ/internal/ears)
+	if(ears)
+		ears.RestoreEars()
+
+/mob/living/carbon/AdjustEarDamage(ddmg, ddeaf)
+	var/obj/item/organ/internal/ears/ears = get_int_organ(/obj/item/organ/internal/ears)
+	if(ears)
+		ears.AdjustEarDamage(ddmg, ddeaf)
+
+/mob/living/carbon/MinimumDeafTicks(value)
+	var/obj/item/organ/internal/ears/ears = get_int_organ(/obj/item/organ/internal/ears)
+	if(ears)
+		ears.MinimumDeafTicks(value)
+
+
+// Kitty ears!!
+/obj/item/organ/internal/ears/cat
+	name = "cat ears"
+	icon = 'icons/obj/clothing/hats.dmi'
+	icon_state = "kitty"
+	color = "#aa4444"
+	transform = matrix(0.7, 0, 0, 0, 0.7, 0)
+
+/obj/item/organ/internal/ears/cat/render()
+	. = mutable_appearance('icons/mob/head.dmi', "kitty", layer = -HEAD_ACC_OVER_LAYER)

code/modules/surgery/organs/organ_internal.dm

@@ -64,6 +64,7 @@
 			log_runtime(EXCEPTION("[src] attempted to remove from a [parent_organ], but [parent_organ] didn't exist! [atom_loc_line(M)]"), src)
 		else
 			parent.internal_organs -= src
+		H.update_int_organs()
 
 	for(var/X in actions)
 		var/datum/action/A = X
@@ -105,6 +106,10 @@
 	insert(H)
 	return 1
 
+// Rendering!
+/obj/item/organ/internal/proc/render()
+	return
+
 /obj/item/reagent_containers/food/snacks/organ
 	name = "appendix"
 	icon_state = "appendix"
@@ -247,7 +252,7 @@
 		to_chat(owner, "<font color='red' size='7'>HONK</font>")
 		owner.SetSleeping(0)
 		owner.Stuttering(20)
-		owner.AdjustEarDeaf(30)
+		owner.MinimumDeafTicks(30)
 		owner.Weaken(3)
 		owner << 'sound/items/AirHorn.ogg'
 		if(prob(30))

code/modules/surgery/organs/vocal_cords.dm

@@ -122,7 +122,7 @@ var/static/regex/multispin_words = regex("like a record baby")
 
 	var/mob/living/list/listeners = list()
 	for(var/mob/living/L in get_mobs_in_view(8, owner, TRUE))
-		if(!L.ear_deaf && !L.null_rod_check() && L != owner && L.stat != DEAD)
+		if(L.can_hear() && !L.null_rod_check() && L != owner && L.stat != DEAD)
 			if(ishuman(L))
 				var/mob/living/carbon/human/H = L
 				if(istype(H.l_ear, /obj/item/clothing/ears/earmuffs) || istype(H.r_ear, /obj/item/clothing/ears/earmuffs))