They can be quite vocal!

From the AKC Standard:
Temperament: The Icelandic Sheepdog is a hardy and agile herding dog which barks, making it extremely useful for herding or driving livestock in the pastures, in the mountains or finding lost sheep. The Icelandic Sheepdog is by nature very alert and will always give visitors an enthusiastic welcome without being aggressive. Hunting instincts are not strong. The Icelandic Sheepdog is cheerful, friendly, inquisitive, playful and unafraid. A confident and lively bearing is typical for this dog.

While some are more vocal than others, there should be a reason for the barking.
 Excessive barking is not typical.

They even howl sometimes too!
 

Spurðann "guarding" our backyard!

They are also very affectionate and lovable breed that loves their family and is generally very gentle with children.

To learn more about the Icelandic Sheepdog and it's temperament,
Please visit here