All voices project a persona whether you plan for one or not. VUIs that are supposedly designed without a persona, as in the first example, consistently score low on personality attributes like "friendly" and "helpful," while scoring high on the "boring" scale.
Thanks to a few hundred thousand years of evolution, we humans can’t help but evaluate speech in terms of personality traits—even if it’s a smartwatch or GPS system that’s talking. This is not opinion. It’s a fact well-documented by sociolinguists (e.g. Labov 1964) that even minimal speech samples will conjure impressions of the speaker’s character. We’ve evolved to be expert at summing up folks based on how they sound.
In one compelling study (Giles & Powesland 1975), teachers were asked to assess eight fictional students based on three things: a sample of written work, a photograph, and a recorded speech sample. The results are surprising—favorable impressions generated by the speech sample overrode negative impressions of both the written work and photograph. Conversely, unfavorable impressions of a student’s speech overrode favorable impressions from the other two sources. Other studies have shown that we rely on speech to evaluate other people in terms of friendliness, honesty, trustworthiness, intelligence, level of education, punctuality, generosity, being romantic, being “privileged,” and suitability for employment. In short: speech is powerful!
The Takeaway: Don’t leave your VUI persona to chance. From the very beginning, create the ideal employee to represent your brand. What are they like? How should they sound? And most importantly, how do they behave? Use this persona as an anchor to ground your user experience and give it a familiar consistency. For more information on persona design, visit Actions on Google and check out this codelab on Crafting a Character.