Vocal Similarity, Timbre, and Persuasion in Consumer–Spokesperson Interactions

Consumers are more easily persuaded by people who are similar to them in looks, behavior, and beliefs. Does similarity's effect on persuasion extend to similarity in how people sound? The authors explore how similarity in vocal timbre influences consumer choice. Using machine learning, they generate an objective measure of vocal similarity (VS) between an individual consumer and a spokesperson using mel-frequency cepstral coefficients to capture vocal timbre. First, using data from 7,002 entrepreneur–investor combinations on Shark Tank , the authors demonstrate the effect of VS on persuasion in investment pitches. Then, in 2,091 Kickstarter campaigns, they find that when a spokesperson's voice is more similar to a large audience's average voice, this results in higher persuasion, measured by fundraised amount and campaign success—a result driven by VS. However, these effects are attenuated when external signals of campaign credibility are present. Finally, in four laboratory studies, the authors show that VS with a spokesperson or recommender leads to greater trust in their competence and positively influences persuasion. The authors find that objective and subjective VS have similar results, with objective similarity mapping onto subjective similarity. They provide a deeper understanding of consumer–spokesperson interactions, including new tools for vocal analytics.