AI Voice Designer
Sierra · London, United Kingdom · 4mo ago
About us
Sierra is the leading platform for customer-facing AI agents, working with many of the world's biggest brands — including The GAP, Rocket Mortgage, SoFi, Sutter Health, and SoftBank — to transform how they serve customers and grow their businesses. We are primarily an in-person company based in San Francisco, with growing offices across North America, Europe, and Asia.
We are guided by a set of values that are at the core of our actions and define our culture: Trust, Customer Obsession, Craftsmanship, Intensity, and a commitment to balancing Family along the way. These values are the foundation of our work, and we are committed to upholding them in everything we do.
Our co-founders are Bret Taylor and Clay Bavor. Bret currently serves as Board Chair of OpenAI. Previously, he was co-CEO of Salesforce (which had acquired the company he founded, Quip) and CTO of Facebook. Bret was also one of Google's earliest product managers and co-creator of Google Maps. Before founding Sierra, Clay spent 18 years at Google, where he most recently led Google Labs. Earlier, he started and led Google’s AR/VR effort, Project Starline, and Google Lens. Before that, Clay led the product and design teams for Google Workspace.
About the role
Voice is one of the most demanding and important surfaces for AI agents. How an agent sounds – its warmth, tone, pacing, accent, and personality – is often the first and most lasting impression a customer has of a brand. Getting it right is equal parts craft, taste, and technical execution.
We're looking for a technical Voice Designer to own that craft. This is a forward-deployed role: you'll work hand-in-hand with Sierra's customers to develop, build, launch, and continuously improve the voices our agents use across our European locales. You are the person who turns a customer's requirements into a living, production-quality AI voice.
You’ll work closely with our voice platform team to implement and tune voices that run at scale on our infrastructure. This will include recording and editing audio, and configuring voices in the Sierra platform (including by making some code-level changes) to bring these voices to life. You’ll partner with the Platform team to build new tools that make voice development increasingly self-serve over time.
This is a hands-on role that blends product sensibility, design taste, customer partnership, and enough technical comfort to work directly in command-line tooling. It sits at the intersection of speech, brand, and engineering.
What You’ll Do
Develop new voices — Design and implement natural-sounding production-ready voices for European locales and key customers, from first concept through launch. Own the end-to-end experience of how a voice sounds—and make deliberate, tasteful choices about accent, pacing, personality, and prosody.
Build and tune voices in the tooling — Tune voices directly using Sierra's platform tooling, including running command-line prompts and submitting pull requests. You're comfortable operating in this environment and iterating quickly.
Direct and record voice talent — Source, direct, and record voice actors. Cut, clean, and prepare audio files for use in the voice pipeline, ensuring recordings meet the quality bar for synthesis.
Partner with customers on requirements — Work directly with Sierra's customers to understand both their hard requirements (locale coverage, latency, telephony constraints, compliance) and soft requirements (brand personality, tone, warmth, register). Translate fuzzy brand language into concrete, buildable voice specifications.
Make voice quality measurable — Help define how we judge whether a voice is good: naturalness, brand fit, intelligibility, and consistency across a conversation. Build feedback loops with customers and contractors that improve voices over time.
Manage a network of language contractors — Employ and manage contractors with native language skills who can partner with you to tune voices in their languages, review nuances a non-speaker would miss, and assess quality improvements over time. Build repeatable processes for evaluating voice quality across locales.
Inform the platform roadmap — Act as the platform team's sharpest internal customer. Collate customer feedback and help scope the tools, levers, and workflows that will let the voice platform team build, launch, and manage voices at scale, and enable voice design to become increasingly self-serve over time.
Past Experience
You’ll have demonstrable professional experience in:
Audio: Professional experience in audio, sound, or voice design — e.g. as a sound designer, audio designer, voice/UX audio designer, or in music/audio production.
Tools: Hands-on recording and editing of speech and audio, including directing voice talent and working in professional studio settings. Fluency with audio tooling and DAWs (e.g. Pro Tools, Logic, Ableton, Audition, iZotope RX) for cutting, cleaning, and preparing audio.
Voice AI: Some experience with speech synthesis / TTS, voice cloning, or conversational AI voice tooling (e.g. ElevenLabs and similar).
Craft & Taste: Demonstrable taste and craft in how things sound — a portfolio or body of work you can point to (voices, earcons/UI sounds, sonic branding, character voices, or similar).
Technical: Comfort with technical, command-line-adjacent tooling: writing basic scripts, able to run CLI commands, make config/code-level tweaks, submit pull requests, and leverage AI coding agents.. Not a software engineer, but comfortable in the terminal.
Customer-facing: Comfortable working directly with clients to deliver on their expectations and timeline.
Our values
Trust: We build trust with our customers with our accountability, empathy, quality, and responsiveness. We build trust in AI by making it more accessible, safe, and useful. We build trust with each other by showing up for each other professionally and personally, creating an environment that enables all of us to do our best work.
Customer Obsession: We deeply understand our customers’ business goals and relentlessly focus on driving outcomes, not just technical milestones. Everyone at the company knows and spends time with our customers. When our customer is having an issue, we drop everything and fix it.
Craftsmanship: We get the details right, from the words on the page to the system architecture. We have good taste. When we notice something isn’t right, we take the time to fix it. We are proud of the products we produce. We continuously self-reflect to continuously self-improve.
Intensity: We know we don’t have the luxury of patience. We play to win. We care about our product being the best, and when it isn’t, we fix it. When we fail, we talk about it openly and without blame so we succeed the next time.
Family: We know that balance and intensity are compatible, and we model it in our actions and processes. We are the best technology company for parents. We support and respect each other and celebrate each other’s personal and professional achievements.
What we offer
We want our benefits to reflect our values and offer the following to full-time employees:
Flexible (unlimited) paid time off
Medical, dental, and vision benefits for you and your family
Life insurance and disability benefits
Retirement plan dependent on country of employment
Parental leave
Fertility and family building benefits through Carrot
Lunch, as well as delicious snacks and coffee to keep you energized
Discretionary benefit stipend giving people the ability to spend where it matters most
Free alphorn lessons
These benefits are further detailed in Sierra's policies, may vary by region, and are subject to change at any time, consistent with the terms of any applicable compensation or benefits plans. Eligible full-time employees can participate in Sierra's equity plans subject to the terms of the applicable plans and policies.
Be you, with us
We're working to bring the transformative power of AI to every organization in the world. To do so, it is important to us that the diversity of our employees represents the diversity of our customers. We believe that our work and culture are better when we encourage, support, and respect different skills and experiences represented within our team. We encourage you to apply even if your experience doesn't precisely match the job description. We strive to evaluate all applicants consistently without regard to race, color, religion, gender, national origin, age, disability, veteran status, pregnancy, gender expression or identity, sexual orientation, citizenship, or any other legally protected class.