The use of voice quality features in addition to prosodic features is proposed for automatic extraction of paralinguistic information (like speech acts, attitudes and emotions) in dialog speech. Perceptual experiments and acoustic analysis are conducted for monosyllabic utterances spoken in several speaking styles, carrying a variety of paralinguistic information. Acoustic parameters related with prosodic and voice quality features potentially representing the variations in speaking styles are evaluated. Experimental results indicate that prosodic features are effective for identifying some groups of speech acts with specific functions, while voice quality features are useful for identifying utterances with an emotional or attitudinal expressivity.