This is a video of Ljufur. He was a very quiet gelding, never nickered or called to anyone or any other horses. I decided to teach him to "talk". I thought about how a horse nickers, by waffling air through their throats and noses. I made that little sound, up close to his nose, and when he exhaled slightly, I clicked and treated him. He caught on quickly, and altho he does it very quietly, he began to nicker when I asked him to.