Speech Engineer

Lisbon, Lisbon, Portugal
Full Time
Mid Level


Who is Defined.ai? Well, from a technical point of view, we leverage the power of a global crowd to provide some of the world’s biggest companies with the high-quality data they need to power their artificial intelligence. We’re instrumental to the progression and development of artificial intelligence and we couldn’t be prouder or more inspired to be involved in an industry that is changing the world.

From a personal point of view, we’re a group of big thinkers, high achievers and creative problem solvers. We bond over our shared love of software engineering, data science, and strong coffee. We like online gaming, running marathons, and team drinks. We celebrate authenticity and diversity and we’re invested in what we do. Our mission? World domination, obviously!

What will you do?

You'll be responsible for designing, developing, and optimizing speech and audio processing systems and technologies. You'll work in a multidisciplinary field that combines elements of computer science, linguistics, signal processing, and machine learning to create and enhance speech recognition, synthesis, and other related applications. Speech Engineers play a crucial role in advancing voice-enabled technologies and natural language processing systems.

A Speech Engineer plays a pivotal role in developing and enhancing voice-driven applications, virtual assistants, and other speech-enabled technologies. Their work contributes to improving user experiences in various domains, from customer service and healthcare to entertainment and smart devices.

Key Responsibilities:

1. Speech Recognition:

   - Develop and implement state-of-the-art automatic speech recognition (ASR) systems.

   - Train and fine-tune ASR models using large datasets.

   - Optimize ASR models for accuracy, speed, and efficiency.

   - Research and integrate cutting-edge ASR techniques and algorithms.


2. Speech Synthesis:

   - Design and implement text-to-speech (TTS) systems for natural and expressive speech generation.

   - Create lifelike and human-like voices for TTS applications.

   - Optimize TTS models for various languages and accents.


3. Acoustic Modeling:

   - Develop acoustic models to represent speech sounds and phonetic features.

   - Improve noise robustness and adaptability of acoustic models.

   - Explore techniques for speaker adaptation and recognition.


4. Language Modeling:

   - Work on language models to improve context and understanding in speech applications.

   - Adapt language models for different domains or applications.

   - Develop techniques for language generation in dialogue systems.


5. Data Processing:

   - Preprocess and clean audio and text data for training speech models.

   - Manage large datasets efficiently and ensure data quality.

   - Explore data augmentation techniques to improve model robustness.


6. Evaluation and Testing:

   - Perform thorough evaluations of speech systems using appropriate metrics.

   - Conduct user studies and collect feedback to improve system performance.

   - Debug and troubleshoot issues related to speech recognition and synthesis.


7. Research and Innovation:

   - Stay up-to-date with the latest advancements in speech and audio processing.

   - Collaborate with research teams to contribute to the development of new algorithms and models.

   - Publish research papers and attend conferences to share findings with the scientific community.


8. Collaboration:

   - Collaborate with cross-functional teams, including software developers, data scientists, and UX/UI designers.

   - Communicate technical concepts effectively to non-technical stakeholders.


9. Documentation and Reporting:

   - Maintain clear and detailed documentation of models, algorithms, and experiments.

   - Prepare reports and presentations to share progress and results with the team and management.


  • 4+ years of practical experience working with ML applications in production.
  • Bachelor's, Master's, or Ph.D. degree in Computer Science, Electrical Engineering, or a related field.
  • Strong programming skills in languages like Python and proficiency in deep learning frameworks (e.g., TensorFlow, PyTorch).
  • Solid understanding of speech and audio processing concepts, including signal processing, linguistics, and phonetics.
  • Experience with ASR, TTS, and other speech technologies.
  • Knowledge of machine learning techniques and algorithms, especially in the context of speech.
  • Proficiency in data manipulation and analysis.
  • Strong problem-solving skills and attention to detail.
  • Excellent communication and teamwork skills.
  • Ability to adapt to rapidly changing technology and research landscapes.


Note: This is a position for people based in Portugal.


You spend a lot of your time at work, so it should be challenging, fun and interesting. At Defined.ai it will be all of those things and more. Here’s what we offer:

  • Flexible working schedule and hybrid model. We know comfort can boost creativity and performance, so you can manage your schedule and work both from one of our modern office spaces or home.
  • Excellent career development opportunities in a high growth company. With us, you can accomplish your career goals and follow a well-described career path with the support of your supervisor.
  • Culture of feedback and continuous improvement. AI is a fast-paced area, so we keep track of tech trends, and we always ask for feedback.
  • An international and diverse team. We have more than 30 nationalities at our 3 locations, and we provide language classes.
  • Continuous training opportunities. You can choose from many options: leveraging hand-on workshops, unlimited access to Udemy and formal development opportunities.
  • We love to have fun together. We joke a lot, and we can't imagine work without fun activities – we already surfed, raced carts and played soccer together.

About Us

Defined.ai offers a platform with multiple data delivery options that leverages machine learning technology and human intelligence to deliver quality-guaranteed training data for AI systems. The platform offers self-service and fully customizable solutions that deliver high-quality project-specific training data, enabling AI products reach market quicker. It is this business model that has allowed Defined.ai to raise a total of $63.6M in funding over 4 rounds. Our value proposition is quality, privacy, speed and scale, covering more than 50 different languages. With strong expertise in speech and natural language processing technologies, we have been serving AI companies and Fortune 500 companies since day one. Defined.ai was founded in Seattle and has offices in Lisbon and Porto.

Privacy Notice: https://defined.ai/dataset/privacy-notice-career


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