In the July 2006 issue of EQUUS, an article by Jennifer Williams, PhD, called “What’s Your Horse Telling You?” describes common horse sounds and what they mean. Here are audio recordings (.mp3 files) of several of those sounds.
Click & Listen: Blow
Click & Listen: Nicker
Click & Listen: Longer Nicker
Click & Listen: Squeal
Click & Listen: Whinny
Compare them to the sounds your horse makes and refer to the EQUUS article to interpret their meanings.