How the interviewer opens it
“Design a system that translates live speech into another language. People can receive captions or translated audio. Keep the delay short enough for a conversation.”
The prompt is vague on purpose. The first minutes are for you. Reduce the prompt to the core features and agree on the numbers before you draw.
What to clarify first
- Session behavior
- Scale
- Read and write mix
- Audio format
- Latency targets and measurement
- Incomplete speech and quality
- Consistency and availability
- Recovery and retention
- Languages and models
- Scope limits
The interviewer has the answers. In a SysRound round, Alex gives these answers, as a real interviewer does.
Scope of a strong answer
Core requirements
- Accept a live audio stream from one speaker
- Show translated captions with provisional text and committed text
- Produce translated audio with a preset voice
- Recover from brief connection failures without replay of heard audio
Usually out of scope
- Train speech or translation models
- Support conferences with several speakers
- Identify speakers or imitate their voices
- Match translated audio to video
What interviewers ask about
- Incomplete speech and corrections
- Later words can change recognition and translation. Captions can change, but the listener cannot forget audio that already played.
- Conversation delay
- Recognition, translation, and synthesis each add delay. A translation can also take longer to speak than its source.
- Stream failures
- Recovery can change translation boundaries and wording. An audio offset cannot safely identify equivalent content in a new translation.
- Traffic bursts
- Model capacity limits active streams, not just request counts. Long queues turn a live conversation into delayed playback.
Common mistakes
- Treats a changing recognition hypothesis as final translated text.
- Waits for complete sentences and ignores continuous speech.
- Sends provisional text to speech synthesis without a correction policy.
- Measures server response time instead of listener delay.
- Removes difficult phrases or fallback sessions from latency results.
- Promises no repeated audio without stable source positions and retained recipient progress.
The bar by level
- Senior (L5/E5)
- Defines commit rules and a complete latency budget. Specifies source-based recovery, partial playback behavior, and worker ownership. Handles model limits and audio backlog.
- Staff (L6+/E6+)
- Defines testable quality and latency contracts for each language pair. Proves recovery safety despite changed translations. Quantifies regional capacity and states limits after recipient state loss.