Senior Researcher

Why AssemblyAI AssemblyAI builds the best-in-class Voice AI models powering the next generation of voice applications. We have a lab, and we also power our own models in our own proprietary inference environment. Our models serve 500M+ inference calls monthly, and process nearly 2 million hours of audio daily. The Voice AI space is at an inflection point; we’re looking for the best talent we can find to join a rapidly scaling team that's defining the future of the industry.

We are one of the most capital-efficient AI companies on the planet - and are rapidly approaching $1M ARR per employee. We sit among the top 5 most revenue-dense teams within the fastest-growing AI companies today. We have thousands of customers building with us including the top startups and world-renowned enterprises, and are serving at tremendous scale: we process nearly 2 million hours of audio daily and handle more than 15 million API calls every day. This is a rare growth-stage opportunity where the business is proven, the revenue is durable, and the growth trajectory is steep and getting steeper. We have a super flat culture and expect our employees to be deeply intimate with the details at all levels.

If you've ever felt buried under layers of bureaucracy, starved of real ownership, or frustrated watching your work disappear into a slow-moving org, AssemblyAI is built differently. The company operates as a true meritocracy, with no heavy planning or approval processes and no gatekeeping on the tools or information you need. For anyone who genuinely cares about voice AI, not as a trend to chase, but as a technology to build, this is the place where the most interesting problems at the most interesting scale are being solved by a team small enough that you'll actually know everyone's name.

About the Role You’ll join the team of researchers and engineers behind AssemblyAI’s foundational speech models. The team trains, fine-tunes, and analyzes these models, and builds the tooling to do that at scale. Your work will become the foundation for every customer around the world who builds Voice AI on our platform.

We’re passionate about Speech AI and the real-world products it makes possible, and we know the field moves fast. Keeping our models ahead means problems can’t stall at team boundaries, so this role is cross-functional by design. You’ll work closely with research, infrastructure, and production engineering. Your job isn’t to hand problems off between those teams. You’ll learn enough of each domain to follow a problem all the way to resolution.

What You’ll Do

• Research and develop new methods that push the frontier of Speech AI.

• Improve the data our models learn from: investigate quality issues, build tooling that surfaces them, and turn what you find into measurable accuracy gains.

• Analyze the accuracy of production models, build evaluation harnesses, and work out which improvements will matter most to customers.

• Partner with researchers and engineers to turn research prototypes into production-ready systems, modernizing model architectures and inference stacks along the way.

• Find and fix performance bottlenecks across our training stack.

What You’ll Need

• Hands-on experience training or adapting (e.g., fine-tuning) frontier speech or multimodal language models.

• Discipline in measurement and analysis. You stay skeptical of results, whether they come from you or a coding agent, until they hold up. You treat an unexplained improvement as a problem and dig in until you understand it.

• Appetite for the whole pipeline. You bring deep expertise in your core area, but when a customer issue traces back to a data problem or an evaluation blind spot, you want to chase it down yourself. The people who thrive here went deep in one area first, then kept expanding outward.

• Enthusiasm for building and sharing tools. Working at the frontier means the tools you need often don’t exist yet. You enjoy buildi...