According to the Modulation Theory, speakers modulate their voice with linguistic gestures, and listeners demodulate the signal in order to separate the linguistic from the expressive and organic information. Listeners tune in to the carrier (the voice) on the basis of an analysis of a stretch of speech and they evaluate its modulation. This is reflected in many perceptual experiments that involved manipulated introductory phrases, blocked vs. randomized speakers, and other non-linguistic variables.
2000. 790-793 p.