Senior Voice AI Engineer

Mission Overview:

This is a consultancy mission at a client site, where you will represent Keystone Solutions as a Senior Voice AI Engineer. As a Keystone Solutions consultant, you will join a team of AI Dev Engineers and Data Scientists to work on a client-facing Voice Bot project, leveraging a hybrid speech stack for best-in-class real-time performance. You will be part of a dynamic consultancy environment, carrying out all responsibilities under the Keystone Solutions consultancy model.

Responsibilities:

• Design and implement streaming pipelines: audio ingest, VAD/endpointing, STT, orchestration/LLM, streaming TTS.
• Own turn-taking: barge-in, interruptions, end pointing tuning, silence handling, latency/accuracy tradeoffs.
• Integrate telephony and app channels (SIP/WebRTC/CPaaS).
• Implement reliability retries, backpressure, rate limiting, fallbacks between open-source and vendor components.
• Work with Data Scientists to define and develop solutions with production constraints, selecting appropriate infrastructure and serving models to meet business requirements.
• Contribute to the automation and deployment of ML pipelines in production environments, including building Docker/VM images and preparing tests.
• Support Data Scientists in using industrial solutions for building and monitoring AI services (CI/CD tools).
• Support IT Production in parameterizing the target environment.
• Ensure models run without errors, are retrained as needed, and are monitored from both IT and business perspectives.

Requirements:

• At least 4 years of relevant engineering experience, with 2+ years shipping streaming speech in production.
• Strong Python skills plus one systems language (Go, Rust, or C++) preferred.
• Experience with streaming audio and WebSockets/gRPC.
• Familiarity with ASR stacks such as Whisper, NeMo, wav2vec2, and neural TTS stacks.
• Practical telephony experience (PSTN/IVR) and/or WebRTC.
• Real-time STT, TTS, and turn-taking/barge-in experience.
• Telephony integration: SIP/WebRTC or CPaaS, codecs (u-law/A-law), 8kHz realities.
• Ability to run evaluations: WER by cohort, latency p95, conversation KPIs.
• Experience integrating open-source STT/TTS and vendor APIs like Gradium.
• Containerization/virtualization, AI platforms & IDEs, CI/CD (gitlab-ci), code/model/data versioning, package management, and dependency management.
• PostgreSQL experience.
• Knowledge of agile methodology.

Preferred Experience:

• Speaker diarization and echo cancellation constraints knowledge.
• Experience in regulated environments (banking, insurance, health).
• Experience building semantic VAD or endpointing models.
• Integration experience with various technologies and infrastructure components.

Soft Skills:

• Excellent oral and written communication skills.
• Results-driven with strong delivery capabilities.
• Attention to detail and rigor.
• Creativity, innovation, and problem-solving abilities.
• Proactive in continuous learning and knowledge improvement.
• Awareness of efficiency and efficacy.
• Ability to think outside existing processes and frameworks.
• Works with energy and empowerment to deliver significant results.
• Constructive, open to change, and receptive to feedback and new ideas.

Language Requirements:

• English: mandatory
• Dutch: a plus
• French: a plus

Work Location & Telework:

• 50% on site and 50% homeworking expected

Why Join Keystone Solutions?

• As a consultant, you will experience a variety of dynamic projects across different client environments, ensuring continuous professional growth.
• Keystone Solutions offers turbo-charged learning opportunities, supporting your development and broadening your expertise.
• We are committed to skyrocketing your ambition, providing a clear path for career advancement within our consultancy framework.
• Being a “K-Stone” means embodying our core values and bringing them to every client engagement, making a real impact in every mission.

Ready to Apply?

If you are ready to tackle technical and strategic challenges in a dynamic consultancy environment, apply today at Keystone Solutions Career Portal.