Gender Bias Affects Voice User Interface Design—for Better or Worse

As voice user interface (VUI) designers, we are often asked a seemingly simple question: Should the system’s voice be male or female? But the answer is not so simple. We have to consider how gender biases can, and often do, affect some aspects of self-service.

Some time ago, I listened to an episode of NPR’s Freakonomics Radio that dealt with gender bias, featuring Myra Strober, Iris Bohnet, Katherine Coffman, and Meghan Sumner, all of them professors at institutions such as Stanford University and Harvard Business School. The show discussed many aspects of gender bias and reviewed research in economics, human psychology, and linguistics.

What caught my attention was when the discussion turned to gender bias based on voice. The design of a VUI, after all, requires a decision on gender, and that decision has consequences. As Sumner, a linguistics professor at Stanford, put it, “As soon as I hear a speaker, how I view that speaker influences everything that happens next.”

According to Strober, a professor emerita at Stanford, from the age of 4, people form biases based on gender. Female and male voices are perceived very differently—even when they are saying the exact same thing.

I’ve seen the effect for myself. A few years ago, I ran a study while working at a utility company. In its IVR system, outage information was recorded using a male voice. Later, with the exact same outage script, we used a female voice. When the female voice spoke the outage information, 51 percent more callers transferred to an agent than when the male voice provided the information. This obviously has huge implications for call center staffing.

So exactly when should an IVR feature a male voice over a female voice, and vice versa?

We need to acknowledge that people do have biases, and the situation isn’t changing overnight. As author and Freakonomics moderator Stephen Dubner put it, “Human nature being what it is—a bundle of cognitive biases and adherence to social norms—[one] can’t solve every problem according to logic. Sometimes you need to design a solution that factors in all these biases and norms.”

Human psychology has proven that, even in 2017, gender biases are alive and well. Sumner’s research found that “a man’s voice that’s rated as not so reliable on its own is rated as more reliable in the context of a woman’s voice, so it gets a kind of boost. And a woman’s voice that’s rated as reasonably reliable alone gets downgraded as less reliable in the context of a man’s voice.” According to Sumner, how we listen to a voice is an unconscious choice, the result of an automatic process within the part of the brain involved with understanding spoken language, but there are filters and social biases at play based on learned behaviors. As soon as a voice is heard, how listeners “hear” the speaker shapes their view and, in Sumner’s words, “influences everything that happens next.”

This has ramifications for VUI design. To have a successful system, designers need to meet customers where they are and chose the type of voice that is right for a particular company, based on careful research.

This brings us back to the thorny question of whether to assign a system a male or female voice. At eLoyalty, we recommend a male voice for most of our applications, for a few reasons. While the female voice is considered “helpful” and “nurturing,” the male voice is perceived as “trustworthy” and “authoritative.” The male voice, then, is perceived to be more efficient in achieving user confidence, and hence, increases containment. Plus, the female voice has a higher frequency; as people age and their hearing diminishes, the higher frequencies go first. When it comes to technical or instructional information, the male voice is listened to more carefully and has a higher “believability.” On the other hand, scripts that are considered “submissive” (in which the system is asked to do something for the caller) usually employ a female voice.

Matching the voice to the audience is a critical component of any system. When choosing a voice talent for yours, you should remember that biases are inherent in most, if not all, people. Like it or not, so long as gender biases are with us, they will play a role in determining the voice of your system.

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