Voice of the Customer (VOC)

A term describing what the customer wants or is willing to pay for. It statistically represents the lower/upper specification  limits (LSL/USL) of a distribution where any data point or observation falling within those limits is considered to be acceptable by the customer and anything falling outside those limits is unacceptable or a defect. This is contrasted with the Voice of the Process (VOP).
Related StatStuff Video: 
   -Section 5-Measure Phase, Lesson #21 - Defining the VOC and Defects