Voice of the Process (VoP) is the objective measurement of what a process actually delivers, its capability, its stability, its variation, expressed in the same terms as Voice of the Customer so the two can be compared honestly. VoP is what turns "we're doing our best" into a testable statement.
Process capability: how consistently the process meets specifications, measured with statistical tools like Cp and Cpk. Process stability: whether the process is in control over time or drifting. Cycle time, lead time, first-pass yield, defect rates. Every important customer requirement should have a corresponding process measurement so the two can be compared.
VoC says what customers need. VoP says what the process delivers. The gap between them is the improvement opportunity. If VoC demands parts within ±0.05mm and VoP shows the process actually produces ±0.15mm, no amount of inspection will close the gap sustainably, the process itself must be improved.
Compare VoC and VoP for every important requirement. Where VoP meets or exceeds VoC, the process is capable, maintain it. Where VoP falls short, improve the process capability, don't just add inspection. Where VoP wildly exceeds VoC, consider whether resources spent on that capability could be redeployed to something the customer values more.
Voice of the Process is the internal counterpart to Voice of the Customer. Together they turn improvement from a matter of opinion into a matter of measurement, and they ensure that the process is being improved on the dimensions that customers actually feel.
