The .380 has about the same loudness as the .38 special. The .32acp is somewhat less loud than the .38s. Any gun, even a .22 fired inside a house is going to be a real shock for someone who has never experienced it without ear protection. 9mm is a step upwards in loudness from .38 special and is louder than a .45.
In most self defense situations any caliber will most likely get the job done. The most important thing is going to be tactics and skill with the weapon.