Voice of the Customer (VOC) and CTQs Explained

4 min read · Updated July 2026

Voice of the Customer (VOC) is the practice of systematically capturing what customers actually need — and translating it into things you can measure and deliver. Improvement that ignores the customer just makes the wrong things more efficient.

Gathering the voice

VOC comes from many sources: interviews, surveys, complaints, reviews, support tickets, and simply observing customers. The goal is to hear needs in the customer’s own words before deciding how to meet them.

From vague need to measurable CTQ

Customers speak in general terms ("I want it quickly"). A Critical-to-Quality (CTQ) requirement turns that into something specific and measurable ("delivered within 2 working days, 95% of the time"). CTQs are what you then design and improve the process to hit.

Why it matters for improvement

Every Lean Six Sigma project should trace back to a customer need. VOC and CTQs keep teams honest — you measure success by what the customer values, not by internal convenience.