Vocal communication of emotion is biologically adaptive for socially living species and has therefore evolved in a phylogenetically continuous manner. Human affect bursts or interjections can be considered close parallels to animal affect vocalizations. The development of speech, unique to the human species, has relied on the voice as a carrier signal, and thus emotion effects on the voice become audible during speech. This article reviews (a) the evidence on listeners' ability to accurately identify a speaker's emotion from voice cues alone, (b) the research efforts trying to isolate the acoustic features that determine listener judgments, and (c) the findings on actual acoustic concomitants of a speaker's emotional state (real or portrayed by actors). Finally, based on speculations about the joint origin of speech and vocal music in nonlinguistic affect vocalizations, similarities of emotion expression in speech and music are discussed.