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Pitch Perfect: Vocal Pitch and the Emotional Intensity of Congressional Speech



Although audio archives are available for a number of political institutions, the data they provide receive scant attention from researchers. Yet, audio data offer important insights, including information about speakers’ emotional states. Using one of the largest collections of natural audio ever compiled—74,158 Congressional floor speeches—we introduce a novel measure of legislators’ emotional intensity: small changes in vocal pitch that are difficult for speakers to control. Applying our measure to MCs’ floor speeches about women, we show that female MCs speak with greater emotional intensity when talking about women as compared with both their male colleagues and their speech on other topics. Our two supplementary analyses suggest that increased vocal pitch is consistent with legislators’ broader issue commitments, and that emotionally intense speech may affect other lawmakers’ behavior. More generally, by demonstrating the utility of audio-as-data approaches, our work highlights a new way of studying political speech.


Corresponding author

*Bryce J. Dietrich, Assistant Professor, Department of Political Science, University of Iowa,,
Matthew Hayes, Assistant Professor, Department of Political Science, Rice University,,
Diana Z. O’Brien, Albert Thomas Associate Professor Political Science, Department of Political Science, Rice University,,


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We are grateful to the anonymous referees at the American Political Science Review and Ken Benoit, who was an insightful and a supportive editor throughout the review process. We also thank Nichole Bauer, Logan Dancey, John Hibbing, Kris Kanthak, Joel Sievert, Danielle Thomson, and conference participants at MPSA (Chicago, IL) and CPAC (Washington University in St. Louis) for their comments and suggestions. Authors’ names listed in an alphabetical order. Replication files are available at the American Political Science Review Dataverse:



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Supplementary materials

Dietrich et al. Dataset

Supplementary materials

Dietrich et al. supplementary material
Dietrich et al. supplementary material 1

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