execute store result score random itemcount run random value 1..4
execute if score random itemcount matches 1 run playsound minecraft:entity.zombie.step hostile @s ^ ^ ^-3 .2
execute if score random itemcount matches 2 run playsound minecraft:entity.zombie.ambient hostile @s ^ ^ ^-3 .2
execute if score random itemcount matches 3 run playsound minecraft:entity.skeleton.ambient hostile @s ^ ^ ^-3 .2
execute if score random itemcount matches 4 run playsound minecraft:entity.skeleton.step hostile @s ^ ^ ^-3 .2 1.2