Let me answer to your questions in sequence.
1. Which Animal produces the loudest sound?
Ans:- Sperm Whale is the animal which produces the loudest sound. It is obviously, a water animal. In land animal, Howler monkey makes the loudest sound.
2. Is it Pet or Wild Animal?
Ans: The intensity of sound that these animals produces is intolerable for normal human beings. 15 mins of exposure of sound with 100 decibels can damage your nerves. So, they can't be petted in the home.
3. What is the intensity of sound these animals produce?
Ans: Sperm Whale produces sounds as high as 230 Decibels and Howler monkeys' sound can go higher than 140 decibels.