Outline the ML inference and labeling pipeline

Q: Outline the ML inference and labeling pipeline

This question evaluates proficiency in ML system design, MLOps, and audio data engineering by focusing on inference and labeling pipeline components such as feature extraction, ASR integration, score calibration and thresholding, data contracts, labeling workflows, drift detection, and model/version management for near‑real‑time and batch processing of multilingual noisy audio. Commonly asked in ML System Design interviews, it gauges practical application skills for specifying end-to-end production pipelines while requiring conceptual understanding of operational concerns like latency, class imbalance handling, calibration, and retraining workflows.

Q: How do I approach ML System Design interview questions?

ML System Design questions require understanding of core concepts and practice. PracHub provides solutions with explanations to help you master ml system design interviews.

Q: What difficulty level is this interview question?

This is a hard difficulty ML System Design question, commonly asked during Onsite rounds at Roblox.

Q: What role is this question designed for?

This question is commonly asked for Software Engineer candidates at Roblox during technical interviews.

Question

Audio Detection System: ML Inference and Data Pipeline (Model Architecture Out of Scope)

Context and Assumptions

Design the machine learning inference and data pipeline for an audio detection system that flags policy-relevant speech and keywords. Assume:

Near real-time decisions on streaming or short audio chunks, plus offline batch processing for analytics/retraining.
Multi-lingual audio, variable noise conditions, and potential background music.
Model architecture is out of scope; focus on pipeline, features, calibration, thresholds, data contracts, labeling, drift, and versioning.

Requirements

Describe:

Feature extraction choices and ordering:
- Denoising and voice activity detection (VAD).
- Acoustic features (e.g., spectrograms, MFCCs) and embeddings.
- Speech-to-text (ASR) and text features, including keyword spotting.
Inference outputs: how scores are computed, calibrated, and thresholded; how to handle class imbalance.
Data contracts for model inputs/outputs and storage plan for transcripts, embeddings, and intermediate artifacts.
Label generation: manual labeling workflows and how to feed labels back (active learning).
Drift detection and operational versioning of models and thresholds.

Outline the ML inference and labeling pipeline

Quick Overview

Audio Detection System: ML Inference and Data Pipeline (Model Architecture Out of Scope)

Context and Assumptions

Requirements

Solution

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