While determining hypervocalization in cats, you also need to take into consideration the breed of the cat as well as the conditions leading to such a situation. Some cats are far more vocal than others. The cat language is made up of a series of different sounds, all of which may mean different things. There are many pleasant sounds like the welcoming purr, the multi purpose murmur and the squeal of pleasure. There are many other simple sounds that indicate aggression like the hiss, growls and spit.
The term hypervocalization generally refers to excessive meowing when it happens as an attention getting mechanism or as a method of releasing excess energy. Before concluding that a cat is hypervocalizing, consider the breed of the cat as well. Some cats are by nature loud and more vocal like the Oriental breeds. So what may be considered excessive for a Persian cat may be absolutely normal behaviour for a Siamese.
Having established that your cat really is hypervocalizing, the next step is to find the reason why. The reason could be very simple. For example, a cat which has been outdoors all along may cry excessively on suddenly being forced to be an indoor cat. However, owners hardly consider such issues while labelling a cat as hypervocal. Many owners are only concerned with how often, how long and how loudly the cat keeps crying. Many cats may have medical reasons behind such behaviour whereas others may resort to hypervocalization just to seek attention.
Hypervocalizing in cats may be due to various reasons, some of which are-
Some of the medical factors which could lead to hypervocalization are-