Speech emotion analysis refers to the use of various methods to analyze vocal behavior as a marker of affect (e.g., emotions, moods, and stress), focusing on the nonverbal aspects of speech. The basic assumption is that there is a set of objectively measurable voice parameters that reflect the affective state a person is currently experiencing (or expressing for strategic purposes in social interaction). This assumption appears reasonable given that most affective states involve physiological reactions (e.g., changes in the autonomic and somatic nervous systems), which in turn modify different aspects of the voice production process. For example, the sympathetic arousal associated with an anger state often produce changes in respiration and an increase in muscle tension, which influence the vibration of the vocal folds and vocal tract shape, affecting the acoustic characteristics of the speech, which in turn can be used by the listener to infer the respective state (Scherer, 1986). Speech emotion analysis is complicated by the fact that vocal expression is an evolutionarily old nonverbal affect signaling system coded in an iconic and continuous fashion, which carries emotion and meshes with verbal messages that are coded in an arbitrary and categorical fashion. Voice researchers still debate the extent to which verbal and nonverbal aspects can be neatly separated. However, that there is some degree of independence is illustrated by the fact that people can perceive mixed messages in speech utterances that is, that the words convey one thing, but that the nonverbal cues convey something quite different.