Expert Voice AI Prompt Engineer (Consultant)

Hearth AI is seeking a top-tier Voice AI prompt specialist for a high-impact consulting engagement. We are refining the user experience for our fast-growing flagship AI receptionist. We are looking for a top-tier, freelance Prompt Engineer who specializes in voice agents to help us achieve a more natural, effective, and human-like conversational flow.
This is a short-term consulting engagement. You will work directly with our product team and CEO to:
Audit & Review: Analyze our current prompt library and conversation flows, identifying areas for improvement in clarity, tone, and efficiency.


Design & Engineer: Design, test, and refine write new, experimental prompts for various scenarios (e.g., call routing, message taking, appointment scheduling, handling ambiguity, repeat callers).


Test & Optimize: Help us structure A/B tests to measure the performance of new prompts against existing ones.
This is the right role for you if:
You have at least 1-2 years of professional experience focused specifically on prompt engineering and conversational design for voice-first AI products (e.g., AI assistants, advanced IVR, voice-controlled applications).
Deep understanding of the nuances of spoken language vs. written language (e.g., handling pauses, interruptions, and non-linear conversations).
Ability to define and embody a specific persona/tone of voice for an AI agent.
Your portfolio demonstrates a deep understanding of Voice User Interface (VUI) design principles. We must see examples of your work for voice agents.
You have a sophisticated understanding of modern prompt engineering techniques (e.g., chain-of-thought, few-shot learning, ReAct) and how to apply them to spoken dialogue.
You are results-obsessed and have direct experience measuring and improving conversational AI performance through A/B testing and data analysis.
You have a "good ear" for what makes a conversation feel natural and can write dialogue that leverages the high-fidelity output of platforms like ElevenLabs.
Bonus points for:
Current or previous experience at a leading voice-first company
Experience with workflow automation tools (n8n, Zapier) and an understanding of how prompts fit into an API-driven system.
Excellent communication skills and the ability to articulate the rationale behind your prompt design choices.
How to Apply: Please begin your proposal with the word "HEARTH" so we know you've read the details. In your proposal, please include:
A link to your portfolio or 2-3 specific examples of voice-related prompt engineering or conversational design work.
A brief paragraph on your experience and philosophy for creating effective prompts for a voice-based AI receptionist to achieve desired user or business outcomes.