What animal is the quietest and why is it a gorilla?

Orangutans are the quietest animals for the following reasons:

Orangutans are animals with the most developed brains and high IQ, so they have strong observation and thinking ability. Orangutans are also cautious. Before they act, they will observe the surrounding environment to ensure their own safety. Because of this behavior, orangutans usually don't make much noise in nature, so they are considered to be the quietest among animals.

In addition, orangutans have relatively little social behavior, and they usually communicate only when necessary, such as in group activities or when looking for food. This may also be one of the reasons why orangutans are considered to be the quietest in the animal kingdom.