What happens when ESL students use Pronounce AI as part of their speaking practice — not just once, but repeatedly, over several weeks?

A new study out of Iowa State University offers a rare, research-backed look at how Pronounce performs in a structured learning environment. The 2025 paper, The impact of generative AI-powered chatbots on L2 comprehensibility, published in the Journal of Second Language Pronunciation, followed English learners over a 3-week intervention and compared outcomes between Pronounce and a general-purpose chatbot (Google Gemini).

Here’s how the study worked — and what it revealed.

Study Design and Tools

The researchers compared two AI chatbot tools:

• Pronounce: A pronunciation-focused chatbot that provides explicit feedback, i.e. direct corrections or suggestions on pronunciation. A general AI chatbot (not specifically for language learning) that provides
• Gemini: A general AI chatbot (not specifically for language learning) that provides implicit feedback by showing a real-time transcript of what the learner says. If the transcript matches the speech, the pronunciation was likely clear; if not, it indicates possible mispronunciations.

The participants were undergraduate and graduate students enrolled in speaking classes at a U.S. university. Each student was assigned to one of three groups:

• Pronounce Group: Practiced speaking with Pronounce.
• Gemini Group: Practiced with Gemini.
• Control Group: Practiced speaking without any chatbot.
  

Each student in the chatbot groups completed nine 30-minute speaking sessions over three weeks, including one-on-one time with a researcher.

Week-by-Week: What They Practiced

Week 1: Open Conversations + Debates

• Students chatted with the bots about personal topics and participated in debates (e.g., “Is social media a force for good?”).
  
• The goal: natural, spontaneous language use.
  

Week 2: Read-Aloud Pronunciation Tasks

• Focused practice with minimal pairs and segmentals.
  
• Students read sentences designed to challenge and highlight common pronunciation errors (e.g., “beat vs. bit,” “Luke vs. look”).
  

Week 3: Role-Plays

• Students assumed different roles in structured dialogues (e.g., a parent vs. a teacher debating homeschooling).
• Encouraged real-time speech production with purposeful interaction.

Only Pronounce offered pronunciation corrections — Gemini simply displayed a transcript of what the bot “heard.”

How Pronounce Was Used in Practice

• Students accessed Pronounce through the web.
  
• They received real-time, structured feedback on their pronunciation, grammar, vocabulary, and fluency.
  
• A dashboard tracked their progress and flagged phrases or segments to revisit.
• Instructors could guide usage and help learners interpret the feedback.

Small Study, Big Signals

While the study was limited in size (just 15 learners across experimental groups), the insights were powerful:

• Learners who practiced with Pronounce regularly — especially with teacher guidance — saw the most improvement in comprehensibility.
  
• They also reported greater awareness of their pronunciation issues, from vowel errors to linking problems.
  
• By contrast, Gemini users received less targeted feedback and tended to reflect on pronunciation only in general terms.
  

“Before using the chatbot, I always neglected my pronunciation. After using it, it’s just like a tutor who points out my mistakes.” — Participant using Pronounce

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Key Findings

• Individual Gains: Some individual learners made notable progress in pronunciation clarity. These were typically the most motivated learners who completed the majority of their chatbot practice sessions. Their improvement suggests that consistent practice was a crucial factor, regardless of which chatbot was used. Participants in the chatbot groups reported.
• ‍Learner Feedback: Participants in the chatbot groups reported positive experiences – as the authors noted, "learners had positive impressions of their experience with the chatbots and believed that their practice contributed to their pronunciation improvement", indicating high engagement and a perception of benefit.

What This Means for Educators and Learners

• Use Chatbots as Supplements: AI chatbots can serve as a useful supplement for out-of-class pronunciation practice. While they may not automatically boost every student’s pronunciation, they provide extra speaking opportunities in a low-pressure setting.
• Encourage Consistency: Improvement was linked to regular practice. Teachers and students might incorporate chatbot speaking assignments (e.g. a few minutes of daily conversation with an AI) to motivate consistent use.
• Boost Confidence: Since students enjoyed using the chatbots and felt it helped, integrating these tools can increase learner autonomy and confidence. Shy students, in particular, might benefit from practicing with a non-judgmental AI partner before speaking in front of peers.

Conclusion

AI chatbots like Pronounce and Gemini show promise as resources for pronunciation training. They are not a replacement for human interaction or instruction, but they offer convenient, on-demand practice. The key takeaway for teachers is to leverage these tools to increase students’ speaking practice. By doing so, especially in a guided and regular manner, teachers can help motivated learners make tangible gains in pronunciation and overall comprehensibility, all while keeping learners engaged and confident.