AI & Technical question

A customer says Sierra’s telephony voice agent feels slow and sometimes talks over callers. How would you isolate where the failure is occurring across telephony, ASR, orchestration, LLM, and TTS; set concrete latency and reliability targets for each stage; and decide which fixes to ship first?

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What this question tests

Whether you can decompose a voice-agent latency and interruption complaint across the full technical stack and set concrete, stage-level targets.

Break the pipeline into its stages: telephony (call setup and audio transport), ASR (speech to text), orchestration (deciding what to do), LLM (generating a response), and TTS (text to speech).
Instrument latency at each stage boundary so you can see exactly where time is lost, rather than only measuring end-to-end response time.
Check barge-in handling specifically for the talking-over complaint, since that is usually an orchestration or turn-taking logic issue, not a raw latency issue.
Set concrete per-stage targets, for example ASR under a few hundred milliseconds, LLM generation streamed to start speaking before the full response completes, and TTS latency minimized through streaming synthesis.
Prioritize fixes by which stage contributes most to the end-to-end delay and which failure (slowness or talking-over) is more damaging to the caller experience, likely talking-over first since it directly disrupts the conversation.
Validate fixes with live call sampling and A/B testing latency and interruption rate before and after each change, not just synthetic benchmarks.

Separates the 'slow' complaint (a latency problem, measurable per stage) from the 'talks over callers' complaint (a turn-taking or barge-in logic problem, not primarily a latency problem), since they have different root causes.
Proposes stage-level instrumentation as the diagnostic method, not guessing which layer is at fault.
Gives concrete illustrative targets per stage, showing real technical fluency in a voice AI stack.
Prioritizes the talking-over issue first since it is more disruptive to trust than raw slowness, a defensible judgment call.

Treating 'slow' and 'talks over callers' as the same problem instead of two distinct failure modes.
No stage-level instrumentation plan, relying only on end-to-end latency.
No prioritization logic for which fix to ship first.

How would you validate a fix at the orchestration layer did not introduce new latency elsewhere?
What would you do if telephony infrastructure itself is the bottleneck and outside your team's control?
How would you set targets differently for different call types, like a quick lookup versus a complex conversation?