Horses make a number of sounds including nickering, sighing, groaning, blowing or snorting and neighing. Horses use these sounds to convey messages, and each sound has its own meaning.
A nicker, produced using the vocal cords and closed lips, is usually a friendly, calm sound used as a greeting. Drawing in a deep breath and releasing it slowly and audibly is a sigh, which expresses relief or relaxation. Groaning can signal pain but is sometimes involuntary or habitual. A quick inhalation that is exhaled in a puff through the nostrils is a blow or snort and indicates excitement, curiosity or expectation. It is also sometimes used as a greeting. Neighing or whinnying is a vocalization made with an open mouth. Depending on tone and body language, it can denote either confidence or anxiety.