AI Voices in Audio Ads: Unpacking Consumer Trust and Engagement

In partnership with the sound branding experts at amp, we’ve been on a mission to answer just that. Our latest research dives deep into the heart of AI-driven advertising, exploring how consumer trust and engagement with synthetic voices stacks up against ads voiced by real people. The findings provide a roadmap for brands to embrace the future of audio advertising with confidence and clarity. 

Unpacking the Voice of AI: Surprising Discoveries 

Collaborating with the neuroscience team at Choreograph and MediaScience, a neuroscience research firm, we conducted a study to measure people’s emotional, neurological, and behavioral responses to both AI-generated and human voices in advertising.  

While respondents in the study expressed a clear preference for human voices, rating ads higher when they believed them to be human-voiced, performance metrics told us a different story. Ads featuring synthetic voiceovers matched the impact of human-voiced ads across key indicators like brand engagement and purchase intent. 

Here are some of our key takeaways: 

Most consumers can't tell the difference between human and synthetic voices in advertising. Less than half of our participants could accurately identify generic AI voices (42% for individual sentences, 47% for full ads). This highlights the remarkable sophistication of today's AI voice technology. 

AI voices held their own in terms of performance, capturing attention and driving purchase intent just as effectively as human voices. Neurological measures showed similar engagement levels. However, respondents consistently scored voices they believed were human as more relatable and emotional. This underscores a preference for human voices consistent with people’s desire for human connection (and potentially their discomfort with unknowingly interacting with non-human agents), even in a technologically advanced world. 

Younger audiences (18-30) were more adept at spotting AI voices than older participants (45+). This isn't surprising; younger generations have grown up immersed in AI technologies, leading to a greater familiarity and perhaps a more discerning ear. 

Despite consumer biases, our neurological findings revealed that the brain processes both AI and human voices in remarkably similar ways when it comes to cognitive attention and physiological arousal. This suggests that the "feeling" of preference might be more about perceived authenticity than actual neurological processing. 

This research confirms that synthetic voices are a viable, scalable solution for brands in advertising today. But as with any powerful tool, thoughtful and transparent application is paramount. 

While synthetic voices can effectively replicate generic human voices, previous studies by our NeuroLab  team within Choreograph have shown the undeniable impact of recognizable "celebrity voices." In a neuroscience study with Spotify, respondents showed up to 35% more brain activity in areas related to emotional engagement when they heard recognizable voices in audio ads. This serves as a reminder that personalities and personal relationships remain potent drivers of impact. 

Summarizing the study, Terence Scroope, Executive Director, Data Strategy, Choreograph, says “AI doesn’t just make media or advertising more efficient, it opens a world of creative possibilities for how brands can better engage consumers. Transparency and authenticity with consumers is key, and when done right, marketers can start to leverage AI in areas like voice DCO, the creation of brand sonic IDs, and more. Brands need to be sure they understand the attitudes of their audiences and the different communities within them and consider testing which types of voices resonate the most and how that may elevate engagement levels.” 

Nancy Hall, Chief Client Officer for WPP Media in the US, adds: “The true value of any new technology for our clients always comes back to the human insight and applications around it. In this case, when we think about why someone may say they prefer a human voice over AI, it’s because of things like tone and inflection. That’s what helps drive brand recall and attachment. If you can recreate that successfully, that’s a powerful asset to brands and one that requires an ethical approach.” 

The Audio Landscape: A Dynamic Shift 

Looking at the broader audio advertising market, we see a dynamic shift. While overall audio ad spend is projected to remain relatively flat globally in 2025 at $26.5 billion, this figure masks significant internal movements. Growth in streaming audio is offsetting a slight decline in terrestrial radio.

In the USA, both audio and print advertising are anticipated to see a slight decline in 2025, reflecting the ongoing shift towards channels offering greater accountability. However, the gains in digital audio, largely fuelled by platforms like Spotify, are a testament to the evolving consumption habits of audiences. The UK, on the other hand, projects a healthy growth in its audio advertising market, with digital audio, including podcasts, leading the charge. 

Our Approach: Rigorous and Revealing 

Our methodology for this study was robust. We collaborated across WPP with amp, and with neuroscience research firm MediaScience, engaging 55 participants in labs across Chicago, New York, and Austin, Texas. Participants, aged 18-30 or 45+, were social media, podcast, and radio users. They were exposed to a rotation of audio clips in a simulated living room environment, allowing us to meticulously measure their responses. Experimental software walked the participants through the audio clips which they would listen to and rate throughout the session.   

Pioneering the Future of Brand Connection 

This research helps empower brands to confidently explore the potential for synthetic voices to further scale their connection and engagement with consumers, while maintaining trust in an increasingly AI-driven world. The opportunities for technology to amplify human connection rather than replacing it are exciting and potentially transformative for marketing approaches when disclosed and pursued transparently.