Language Lead - Japanese

About the role

You will serve as the primary linguistic authority for Japanese within our voice AI initiatives, owning the end-to-end quality and integrity of the language throughout the product lifecycle. You will act as the central hub for all language-related queries, making final decisions on annotation alignment and edge cases specific to Japanese. This role requires you to manage linguistic consistency across datasets, monitor how the language performs in production, and investigate any degradation or customer-reported issues. You will apply deep linguistic expertise to refine annotation guidelines and ensure they accurately reflect the nuances of Japanese speech. You will independently drive projects that demand precision, cultural awareness, and strict adherence to rubric definitions. You will serve as the main liaison between the engineering team and Japanese language data, ensuring that the voice AI behaves naturally and accurately for Japanese users. This position is critical for maintaining the high standards required for human-like AI interaction in the Japanese market.

Key facts

What you'll do

• Answer questions from annotators about guidelines, edge cases, or language-specific issues via an agreed project communication channel.
• Cascade new feedback, instructions, or rubric updates to annotators working on your projects.
• Listen to annotator-rated audio files and check whether their ratings and written feedback align with the rubric.
• Prepare written quality assessments for annotators with specific examples and recommendations.
• Listen to TTS output and provide ground truth assessments of pronunciation, prosody, and naturalness in your language.
• Update or expand sections of the annotation guidelines when you find gaps or edge cases.
• Prep and run calibration meetings with annotators.
• Hold office hours on a mutually agreed schedule during active studies so annotators can ask questions in real time.
• Develop onboarding materials and resources for new annotators.
• Write QA reports on annotation quality and calibration outcomes.
• Review production audio in your language and flag quality issues to the team.
• Investigate language-specific issues reported by customers and identify root causes.
• Audit datasets for linguistic accuracy, completeness, and consistency.
• Coordinate with the Human Evals Manager on project deliverables and timelines.

Requirements

• Native-level proficiency in Japanese as spoken in Japan.
• Experience with data annotation, transcription, or language quality assurance.
• Strong foundation in linguistics or a related field, with the ability to apply concepts like phonetics, prosody, and intonation when evaluating speech and writing annotation guidelines.
• Strong written English proficiency. All guidelines, feedback, reports, and team communication are in English.
• Ability to write clear, structured instructions and deliver specific, actionable feedback to annotators.
• Comfortable working with data and metrics such as inter-rater agreement scores, audit spreadsheets, and structured feedback templates.
• Self-directed and able to manage feedback cycles, QA reviews, and data projects without close oversight.
• Must be authorized to work in your country of residence and comply with all local laws regarding contract work.

Nice to have

• Experience writing or maintaining annotation guidelines or rubrics.
• Experience training, mentoring, or managing other annotators.
• Experience with audio evaluation, TTS, or STT.
• Conversational spoken English proficiency for meetings and calibration syncs.
• Experience working with distributed, remote teams.

Practical notes

• Roughly 40 hours per week with flexibility in scheduling.
• Project hours may vary depending on active studies, data projects, and product needs.
• Participation in periodic coordination meetings during US Pacific hours is expected.
• This is a 1099 contract opportunity and will not be eligible for the benefits below.
• Language Leads work on an ongoing basis, renewable by mutual agreement.
• You will control your own methods for completing assigned work, supply your own equipment, and are responsible for your own taxes.
• You must be authorized to work in your country of residence.

Note: Cartesia participates in E-Verify and will provide the federal government with Form I-9 electronically. You will be required to provide documentation verifying your identity and employment authorization in the format prescribed by Section 274b of the Immigration and Nationality Act to confirm you are authorized to work in the United States. You must be able to provide this documentation within three business days of your start date.