Voice AI's Rising Bar: Rime CEO Lily Clifford on Conversation Quality

What makes an AI voice worth talking to? Rime founder Lily Clifford thinks the next breakthrough in voice AI isn't a more natural-sounding voice—it's a conversation you actually want to keep having.

On this episode of The Flywheel, M13 Partner Morgan Blumberg sits down with Lily Clifford, co-founder and CEO of Rime. Before Rime, Lily was earning a linguistics PhD at Stanford, researching the acoustic physics of how humans produce speech. Lily’s since built Rime into voice AI that powers roughly 100 million phone interactions a month across healthcare and financial services, and has a clear, differentiated view of where voice goes next.

Lily breaks down why the next wave isn't a smoother-sounding voice, but conversations people don't want to hang up on and what that means for anyone building with voice right now.

In this episode:

• Why "quality of interaction" is a far higher bar than natural-sounding audio—and why there's no margin for error when someone expects a human
• What an independent study of roughly 100,000 calls revealed about why people stay on the phone longer with Rime than with Eleven Labs or Google
• Lily's take on why you can't actually build on today's most impressive frontier voice models
• Why enterprises will start building their own voice stacks—and the building blocks that are still missing
• Why a linguistics-first team treats "impossible" problems (like how to pronounce the word "live") as the whole point

Chapters: 

• 00:00 — Why "natural" isn't the bar for voice AI 
• 01:00 — 25th Street Recording: where Rime made its first recording 
• 04:00 — Quality of interaction vs. quality of voice 
• 08:29 — The Miravoice study: ~100,000 calls and the 10-second effect 
• 12:12 — Build vs. buy: why frontier voice models aren't buildable 
• 16:13 — The building-blocks problem and the enterprise "game of telephone" 
• 21:40 — Will enterprises build voice in-house? The SaaS parallel 
• 26:55 — A linguistics-first team, and leaving a Stanford PhD 
• 36:23 — Why chase an "impossible" problem 
• 41:00 — Language, vowels, and what makes us human 
• 46:15 — What keeps Lily going

Follow The Flywheel on Spotify or Apple Podcasts for more conversations with the founders building at AI's frontier. 

Learn more about Rime at rime.ai and M13 at m13.co.