---
title: 'Applied Researcher, Audio Post-Training at Cartesia'
canonical: 'https://feeny.ai/job/applied-researcher-audio-post-training-cartesia-san-francisco-vree3x7tbsk0'
type: 'job'
last_seen: '2026-09-15'
---

# Applied Researcher, Audio Post-Training at Cartesia

- **Company:** Cartesia
- **Location:** San Francisco, CA
- **Employment:** full-time
- **Work type:** onsite
- **Posted:** 2026-07-20
- **Last confirmed live:** 2026-09-15
- **Apply:** https://jobs.ashbyhq.com/cartesia/eeac6a77-eac5-4d72-b3d4-97d53cac4c89

## Job description

## About Cartesia

Our mission is to architect AI that learns from and interacts with the world like humans do. We're pioneering the model architectures that will make this possible. Our founding team met as PhDs at the Stanford AI Lab, where we invented State Space Models or SSMs, a new primitive for training efficient, large-scale foundation models. Our team combines deep expertise in model innovation and systems engineering paired with a design-minded product engineering team to build and ship cutting edge models and experiences. We're funded by leading investors at Index Ventures and Lightspeed Venture Partners, along with Factory, Conviction, A Star, General Catalyst, SV Angel, Databricks and others. We're fortunate to have the support of many amazing advisors, and 90+ angels across many industries, including the world's foremost experts in AI.

## About the Role

On the Audio Post-Training team, you’ll be building and improving the capabilities that define how the rest of the world interacts with our generative audio models. This team is where customer needs meet research, and covers the full spectrum of modeling from ideation through productionization. On any given day, you might design evaluations to reliably measure new capabilities, build processing pipelines to improve data quality, experiment with finetuning and reinforcement learning approaches to refine model behavior, and more. This role is broad, and cross functional. Members of this team should combine broad research experience with a deep care about building to solve for customer needs and a strong sense of end-to-end ownership. You should be excited to synthesize customer complaints into a holistic understanding of capability gaps, to drive research efforts across data, model training, and evaluation to close those gaps, and to communicate those improvements to product and customer stakeholders. Ultimately, you will be responsible for creating the model experience that the rest of the world sees.

## Your Impact

- Collaborate with product teams to understand and prioritize customer asks
- Cut through the ambiguity of vaguely described behavioral problems to make concrete research plans.
- Ideate and experiment across the full modeling stack, including data processing, synthetic data, SFT, RL, and evals to solve for high priority model capabilities
- Root cause failures in production models and understand how to fix them in future model iterations
- Decide which features and capabilities are ready for public launch

## What You Bring

- Strong fundamentals in software engineering, machine learning, debugging complex systems, and the ability + desire to learn quickly.
- Experience building and ensuring quality of large multilingual datasets.
- Experience training and debugging generative models (speech, text, or multimodal), especially SFT, RL, synthetic data, and evaluation (both human and automated).
- Excitement about solving problems grounded in real customer needs, not just benchmarks.
- Bonus points if you have native proficiency in other languages!

Note: Cartesia participates in E-Verify and will provide the federal government with Form I-9 information to confirm employment eligibility after hire.

More Details 🏢 In-office policy: We’re an in-person team based out of offices in 🇺🇸 San Francisco, 🇬🇧 London and 🇮🇳 Bangalore. We love being in the office, hanging out together, and learning from each other every day. 🌎 Visa sponsorship: We provide visa sponsorship support and assess each circumstance on a case-by-case basis. However, visa sponsorship is dependent on many factors, including the role you are applying for, and the location you are going to be based, and so we can't always guarantee success. Your Recruiter will work with you to understand your visa sponsorship needs from the first call. 🚢 We ship fast. All of our work is novel and cutting edge, and execution speed is paramount. We have a high bar, and we don’t sacrifice quality or design along the way. 🤝 We support each other. We have an open & inclusive culture that’s focused on giving everyone the resources they need to succeed.

Our Benefits (US Employees Only) 💰 Compensation Competitive base salary alongside attractive equity package. 🩺 Health Insurance Fully covered medical insurance along with dental and vision for you and your family. 🧑‍🧑‍🧒‍🧒 Parental Leave 9 weeks paternity & 12 weeks maternity leave 🏦 401(k) 🚆 Commuter Allowance A monthly stipend to help you get to and from the office. 🏖️ Flexible PTO Take as much time as you need to recharge your batteries. 🍲 Meals & Snacks Lunch, dinner and plenty of snacks, provided daily. 🦖 Your own personal Yoshi

Our Commitment to Equal Opportunity Cartesia is an equal opportunity employer. We consider qualified applicants without regard to race, color, religion, sex, national origin, age, disability, veteran status, genetic information, or any other legally protected status.

## About Cartesia

## Company Overview

- **One-liner**: Cartesia builds next-generation foundation models using state space models (SSMs) to deliver ubiquitous, interactive, real-time AI that runs wherever you are.
- **Entity Type**: Private (Series A-II; total funding $191M)
- **Headquarters**: San Francisco, California, United States
- **Founded**: 2023
- **Founders**: Karan Goel (CEO), Albert Gu (Chief Scientist & Co-founder), Brandon Yang (Co-founder), Arjun Desai (Co-founder)

## Core Business

- **Primary industry/industries**: Artificial Intelligence – foundation models, real-time voice AI, multimodal AI
- **Target customers**: B2B – developers and enterprises building real-time AI applications in healthcare, robotics, gaming, customer service, localization, recruiting, finance, and more.
- **Mission or purpose statement**: “Build the next generation of AI: ubiquitous, interactive intelligence that runs wherever you are.”

## Products & Services

- **Sonic**: The world’s fastest generative voice API – a streaming text-to-speech API that supports laughter and emotion, designed for real-time voice agents (SaaS / API).
- **Ink**: Likely a multimodal generation product (text-to-image or visual) – part of Cartesia’s broader SSM platform.
- **Agents**: A framework or tool for building real-time AI agents using Cartesia’s foundation models.
- **Core foundation models**: State-of-the-art SSM-based models for text, audio, video, images, and time-series data (research-backed platform).

## Market Standing

- **Valuation/Market Cap**: Not disclosed (private company)
- **Key Metric**: Total Funding – $191M  
  - Seed Round (Dec 2024): $27M  
  - Venture Round (Nov 2025): $100M  
  - Series A (Mar 2025): $64M (latest round)
- **Notable Investors/Partners**: Index Ventures, Lightspeed Venture Partners, Kleiner Perkins, NVIDIA, A* Capital, and more.
- **Growth Signals**:  
  - 88 employees with +6.5% monthly headcount growth  
  - 34 active job postings (+17.2% monthly, +9.7% quarterly)  
  - Website traffic up +73.2% year-over-year (380k monthly visits)  
  - Team hails from Stanford, CMU, Meta, Scale AI, Cruise, and other top AI labs

## Competitive Advantages

- **Pioneering SSM Architecture**: The founding team invented State Space Models (SSMs) at Stanford AI Lab – a subquadratic alternative to transformers that enables higher quality and far more efficient inference for real-time, multimodal AI.
- **Speed & Efficiency**: Sonic (voice API) is marketed as the world’s fastest generative voice API, critical for latency-sensitive applications.
- **World-class Backing**: Supported by top-tier VCs (Index, Lightspeed, Kleiner Perkins) and NVIDIA, providing both capital and ecosystem access.
- **Research‑to‑Product Pipeline**: Direct lineage from academic breakthroughs to production-grade APIs, giving them a deep technical moat.

## Strategic Focus

- **Real‑time, Ubiquitous AI**: Expand from voice to broader multimodal capabilities, powering interactive AI that runs on edge and cloud.
- **Vertical Expansion**: Target high‑value use cases in customer service, healthcare, gaming, robotics, and localization.
- **Talent Acquisition**: Aggressively hiring across research, engineering, product, and go‑to‑market roles (34 current openings).
- **Open‑source & Community**: Maintain a developer‑friendly stance with a Discord community and free trial of Sonic.

## Why Work Here

- **Cutting‑edge AI Research**: Work alongside the original inventors of SSMs and contribute to foundational AI architecture.
- **Fast‑growing Startup**: 88 employees with rapid headcount growth and significant funding – offers ownership and impact.
- **Values‑driven Culture**: “Get the fundamentals right,” “Build to solve problems,” “Aim beyond what’s possible,” “Be honest,” “Have fun with it.”
- **Remote‑flexible**: Presence across 5 countries (US, UK, India, South Korea, Switzerland) suggests a distributed team with flexible working arrangements.
- **Engineering‑heavy**: 39% of staff in technical roles, 8% in research – strong emphasis on technical excellence.
- **Notable Perks**: Not explicitly listed, but a high‑caliber team (Stanford, Meta, Scale AI) and top investor backing indicate competitive compensation and a vibrant startup environment.

## Sources

1. [cartesia.ai](https://cartesia.ai/company/)
2. [LinkedIn – Cartesia](https://www.linkedin.com/company/cartesia-ai)
3. [CB Insights – Cartesia](https://www.cbinsights.com/company/cartesia)
4. [Lightspeed Venture Partners – Cartesia](https://lsvp.com/company/cartesia/)
5. [Jobs.ashbyhq.com – Cartesia Careers](https://jobs.ashbyhq.com/cartesia)

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