Can cats communicate?
Cat vocalizations have been categorized according to a range of characteristics. Originally suggested by Mildred Moelk, cat sounds are often divided into three main classes:

sounds produced with the mouth closed (murmurs – purring, trilling)
sounds produced when the mouth is first opened and then gradually closed (meowing, howling, yowling)
sounds produced with the mouth held tensely open in the same position (growls, snarls, hisses, spits, chattering, and chirping).
In 1944, Moelk published the first phonetic study of cat sounds. She listened very carefully to her own cats and organized their sounds into 16 phonetic patterns divided into three main categories. She also used a phonetic alphabet to transcribe or write down the different sounds. She claimed that cats had six different forms of meows to represent friendliness, confidence, dissatisfaction, anger, fear and pain. Moelk classified eight other sounds involved in mating and fighting by listening to the animals in her yard and on the street.

Brown et al. categorized vocal responses of cats according to the behavioral context: during separation of kittens from mother cats, during food deprivation, during pain, prior to or during threat or attack behavior, as in disputes over territory or food, during a painful or acutely stressful experience, as in routine prophylactic injections and during kitten deprivation. Less commonly recorded calls from mature cats included purring, conspecific greeting calls or murmurs, extended vocal dialogues between cats in separate cages, "frustration" calls during training or extinction of conditioned responses.

Miller classified vocalizations into five categories according to the sound produced: the purr, chirr, call, meow and growl/snarl/hiss.

Owens et al. categorized cat vocalizations based on their acoustic structures. There are three categories: tonal sounds, pulse sounds, and broadband sounds. Tonal sounds are further categorized into groups of harmonically structured sounds or regular tonal sounds. Pulse vocalizations are separated into pulse bursts and hybrid pulse bursts with tonal endings. Broadband sounds are separated into four groups: non-tonal broadband sounds, broadband sounds with tonal beginnings, broadband sounds with short tonal elements, and broadband sounds with long tonal endings.