Zola was played recordings of her own growls and moans, as well as those from other seals she had never met. To check if she could classify the sounds, she had to respond with a matching call type. This meant that when I played her a growl, she was correct if she growled back. If I played her a moan, she was correct if she moaned back. Throughout testing, Zola was played 140 different sounds, recorded from three different seals, which she had not heard before. She responded correctly 90% of the time, showing that she could classify new calls into the right category.