The sounds a cat make is split into three groups: vowel sounds, murmur sounds and hostile calls. Vowel sounds produced when a cat opens and closes its mouth like a meow, howl or chatter. Murmur sounds typically formed with the mouth closed like purr, trills and chirrups whilst tense sounds are made with an open mouth used in offensive or defensive interactions like yowl, hiss, snarl, spit and growl.