A Dynamic Model of Speech for the Social Sciences
98 Pages Posted: 10 Dec 2019
Date Written: November 22, 2019
Speech and dialogue are the heart of politics: Nearly every political institution in the world involves verbal communication. Yet vast literatures on political communication focus almost exclusively on what words were spoken, entirely ignoring how they were delivered---auditory cues that convey emotion, signal positions, and establish reputation. We develop a model that opens this untapped information to principled statistical inquiry: the model of audio and speech structure (MASS). Our approach models political speech as a stochastic process shaped by fixed and time-varying covariates, including the history of the conversation itself. In an application to Supreme Court oral arguments, we demonstrate how vocal delivery signals crucial information---skepticism of legal arguments---that is indecipherable to text models. Results show that justices do not use questioning to strategically manipulate their peers, but rather engage in genuine fact-finding efforts. Our easy-to-use R package, speech, implements the model and many more tools for audio analysis.
Keywords: Speech dynamics; Signal processing; Conversation; Emotion; Hidden Markov model; Latent process
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