noun
Colloquial and somewhat rare; used to describe a person's voice that is noticeably big or booming, often in a casual or humorous way.
あの人のデカ声、隣の部屋まで聞こえるよ。
That person's loud voice can be heard all the way to the next room.
デカ声で話さないで、静かにして。
Don't talk in a loud voice; be quiet.