The Highs and Lows of Voice Pitch

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“I’m always interested in some aspect of us. What makes humans tick? Why are we the way we are?”

While some aspiring academics gravitate towards established topics or research labs, College of Health Professions Associate Professor of Communication Science and Disorders Sethu Karthikeyan, PhD, took a different route. She has spent her academic career exploring topics in which she is curious and intellectually consumed by, no matter the external interest—a route that by her estimation has been a bit more circuitous, but one that has been rewarding at every step along the way.

Primarily, Karthikeyan has used speech and language as a tool to better understand human nature. Says Karthikeyan, “It’s so broad and multidisciplinary, so the question is the king. It drives your literature review, and you really have to dip into psychology, biology, anthropology, and sociology and integrate them into your work.”

“It’s so broad, so multidisciplinary, so the question is the king. It drives your literature review, and you really have to dip into psychology, anthropology, and sociology and integrate them into your work.”

Recently, she’s been exploring the phenomenon of voice pitch in relation to sexual preference. As Karthikeyan explains, on average, men have a vocal fundamental frequency (objective measure of voice pitch), that is five standard deviations below the female vocal pitch. This dimorphism, as it's called, is not unique to humans. However, the unusually high degree of dimorphism among apes suggests that this is not just something we’ve inherited, but has also been a target of evolutionary selection.

For Karthikeyan, the main question is: why?

“Men with deeper voices may be attractive to potential mates because it is associated with some aspect related to health, physical formidability, social competence and/or status. This may have been a female mate preference beneficial in ancestral environments. That’s based on the intersexual selection proposal by Darwin,” explains Sethu. “The other argument is that it could be a result of male-to-male competition, i.e., intrasexual selection, where individuals of the same sex compete against one another for highly sought after resources, including mates.”

According to Karthikeyan, it appears both these mechanisms factor into why the dimorphism in voice pitch exists—just with one of those factors being arguably a bit more prominent as detailed in the theoretical piece by David Puts (2010) and further supported by a recent study by his team (see Aung et al., 2023).

“What’s interesting is when we consider the two mechanisms together, intrasexual competition appears to be the stronger driving force. For example, the lowering of men’s voice pitch has larger effects on perceptions of dominance than attractiveness.”

Karthikeyan sees this review as a launching pad to explore other avenues of related research, such as how social context may make one change their voice pitch and other aspects of speech such as articulation and fluency and how these could influence one another.

“It is important to remember that the social context makes one change one's voice,” she explains. “Pitch is determined by the size of my vocal folds, but how much I tense or relax my folds, which affects pitch modulations, could depend on the context that is triggering my physiological response, for example, stress levels. Also, changes in vocal pitch seem to be associated with other psychological measures that look into your propensity to empathize with others, just to cite one example.”

Karthikeyan is excited to continue to delve into complex questions at the intersection of communication sciences and disorders and evolutionary psychology. She is currently exploring how articulation may change based on cultural identities and conversational partners, evaluating how foreign-accented and native-accented speakers accentuate or mitigate certain syllables in American English depending on their conversational partner. She’s also recently received approval for a book proposal alongside collaborators, Glenn Geher, Psychology department in SUNY New Paltz, and Andrew Gallup, Behavioral Biology Program at Johns Hopkins, which would take the form of an evolutionary psychology handbook, an edited volume published by the Oxford University Press.

All in all, Karthikeyan hasn’t stopped following her curiosity—and by doing so, has set an admirable example for her students and colleagues alike

“I need to be very curious about the research question; and need to make sure I have the space to think independently about everything leading to that question without falling into the trap of blindly following mainstream narratives. I’ll always ask myself; why did I get into this in the first place?”