Rime has raised $24 million in Series A funding to expand its enterprise voice AI platform and support the development of speech-to-speech models designed for complex and regulated environments. The round was led by M13, with participation from Twilio Ventures, Corazon Capital, Unusual Ventures and other existing investors. Morgan Blumberg, a partner at M13, will join Rime’s board of directors in connection with the financing.
Rime plans to use the new capital to expand its proprietary conversational speech dataset, strengthen its technical infrastructure and make strategic hires across engineering and research. The company said it intends to increase its data investment by approximately tenfold as it works to develop more expressive, accurate and contextually appropriate voice models.
The company also appointed Rafael Valle as chief science officer. Valle previously led audio research at Meta’s Superintelligence Labs and will oversee research and product innovation as Rime expands its speech technology capabilities.
Founded in 2022, Rime develops voice AI models using what it describes as a linguistics-first approach. Instead of concentrating only on model size or generalized measures of naturalness, the company studies the linguistic characteristics that influence how speech is interpreted, including pronunciation, cadence, speed, tone and conversational appropriateness.
Rime was founded by CEO Lily Clifford, who was pursuing a linguistics Ph.D. at Stanford University; Brooke Larson, a linguist who previously worked on Amazon Alexa; and Ares Geovanis, a Stanford-trained engineer.
The company combines academic speech science with a large collection of expressive, multilingual conversational speech. Rime believes that building effective speech-to-speech systems requires the ability to measure qualities such as empathy, relevance and appropriateness, which can be difficult to evaluate through conventional software testing.
Rime’s technology is focused on the modeling layer of enterprise voice applications. Its speech models are integrated into products operated by healthcare, financial services and customer-experience companies, where accurate pronunciation, reliability, regulatory compliance and customer trust are particularly important.
The company said its technology powers nearly 100 million phone calls each month for customers including Mayo Clinic, Dialpad, Upstart and Asurion. Across its broader customer base, Rime supports more than 100 million monthly voice interactions.
Rime has gained traction in healthcare and financial services, where voice systems may need to correctly pronounce medical terminology, financial products, customer names and other specialized language. The platform is also designed to support organizations with requirements related to the Health Insurance Portability and Accountability Act.
The company said the performance of its technology was recently evaluated in an independent study conducted by Miravoice. The study assessed 12 voices from three providers across approximately 100,000 calls.
According to Rime, the study found that its voices produced statistically lower rates of customers hanging up during the introduction compared with major competitors. Rime also recorded the fastest median completion time among the providers evaluated.
The company believes the results demonstrate how linguistic details such as cadence, pacing and pronunciation can affect measurable business outcomes, including whether customers remain on a call and how quickly an interaction is completed.
Rime plans to use the Series A financing to advance what it calls voice interaction models: speech systems designed not only to generate realistic audio but also to respond in ways that are appropriate to the context and purpose of a conversation.
The company’s longer-term goal is to create speech infrastructure that can be used by developers and enterprises to build real-time AI products capable of operating reliably across high-volume and regulated use cases.
KEY QUOTES:
“The things that matter most in conversation are the hardest to pin down. Response relevance is hard to specify; speech appropriateness is hard to verify. There’s no unit test for sounding like you care. That’s exactly why this is a design problem, not just an engineering one. We’re building voice interaction models, systems where our linguistic judgment and taste become research instruments, not afterthoughts. With this new funding and Rafael Valle joining as Chief Science Officer, we’re 10x-ing our data investment to define the design language of conversational general intelligence.”
Lily Clifford, Co-Founder and CEO of Rime
“In financial services, the stakes for voice AI are exceptionally high and accuracy is a requirement for customer trust. Rime’s ability to handle complex financial use cases with precision allows us to build experiences that truly serve our customers’ needs.”
Shiv Indap, Upstart
“The design patterns that will define the speech-to-speech era of AI haven’t been built yet. Rime is doing the foundational work by combining frontier AI with deep linguistic expertise to create the speech infrastructure the next generation of AI products will rely on. Lily, Ares and Brooke are building Rime with the rare combination of world-class AI research and deep linguistic expertise to deploy real-time voice people can trust in complex, regulated environments.”
Morgan Blumberg, Partner at M13
