This approach is particularly advisable when doing a process improvement project, or in case of smaller product/services scope.

To understand the voice of the customer means to understand what the customer perceives as added value; in other words what he is willing to pay for. In order to understand the voice of the customer we must listen to what the customer has to say.
The voice of the customer is an exercise per product/service and is not generically applicable for the whole portfolio.
VOC is typically done in four steps:

Steps
1. Identify customers:
For the product(s)/service(s) involved: distinguish the different customer segments. (This has already been performed in the business context.)

2. Plan collection of customer needs:
Based on the customer segmentation, per customer segment can be determined how the customer needs can be gathered. Depending on time and scope restraints this can vary from focus interviews, to customer surveys, but also internal sources, such as:
• Warranty logs
• Satisfaction surveys
• Call centre logs
• Complaints / compliments
• Customer contacts
• Contract cancellations
• Market share changes
• Defections/acquisitions
• Customer referrals
• Web page hits
• Sales reporting
• Others….
Plan who will collect the data in which timeframe.

3. Gather customer information:
Execute the collection plan: use sources described in step 2:
• Record the needs and also Minutes of Meetings
• Get to ‘root needs’ during discussions using ‘5 whys’ technique
• Evaluate unspoken needs
• Extract statements of needs from documents
• Summarize surveys and other data
• Prioritize needs using ranking, rating, paired comparisons or conjoint analysis

4. Organize data
• Use affinity diagrams to categorize & consolidate customer needs
• Breakdown general customer needs into more specific needs
• Maintain dictionary of original meanings to avoid misinterpretation
• Use function analysis to identify key unspoken, but expected needs

5. Analyze customer information:
translate the customer needs to requirements and classify them using Kano (delighters, satisfiers: more is better, must-be’s, indifferent and reverse). Supporting techniques are affinity diagrams and tree diagrams.

6. Determine customer needs:
Formulate CCRs (critical to customer requirements).
A CCR is a quantifiable (thus measurable) characteristic of the product/service for which targets, variation and allowable defects can be established. CCR guidelines:
o the CCR must be directly correlated to customer needs
o the CCR must be easy to understand
o the CCR promotes appropriate analysis, design and action

Based on the VOC, the requirements can be further detailed using the House of quality technique.