Guttural describes a hoarse sound made in the back of the throat. Your friend's voice might get low and guttural just before he bursts into tears.
Growls and cries are often described as guttural. The Latin word guttur, "throat or gullet," is the root of guttural. That's why sounds that are deep and croaked as if they come from the back of your throat are guttural. In linguistics, speech sounds that start in the throat, like the consonants k and g, are called guttural consonants, and there are even guttural languages which contain many guttural sounds.
