When you start using items that have a MaxItemUseDuration the sound "item.armor.equip_generic" is played.
- milk bucket
- drinkable potion
These items can be found by searching in the decompiled version for classes overwriting the net.minecraft.item.Item.getMaxItemUseDuration(ItemStack) method and returning a value greater than 0.
- Join a server
- Set your gamemode to survival
- Have another player join the server
- Start drawing back your bow with the first player
- The second player will hear "item.armor.equip_generic"
The following is based on decompiled version of Minecraft 1.9 using MCP 9.24 beta. All method and class names are the names used in the decompiled version.
The reason is very likely that the method net.minecraft.server.management.PlayerInteractionManager.func_187250_a(EntityPlayer, World, ItemStack, EnumHand) acts for items with a MaxItemUseDuration greater than 0 as if the item changed.