Voice of the customer (VOC)

The Voice of the Customer (VOC)

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Author: Daniel Croft

Daniel Croft is an experienced continuous improvement manager with a Lean Six Sigma Black Belt and a Bachelor's degree in Business Management. With more than ten years of experience applying his skills across various industries, Daniel specializes in optimizing processes and improving efficiency. His approach combines practical experience with a deep understanding of business fundamentals to drive meaningful change.

The Voice of the Customer (VOC)

VOC Voice of the customer is about understanding who your customers are which could be both internal and external. If you know who they are, do you know if they are satisfied with the product or service you offer? And do you understand what is important to them? If you don’t know you should ask them.

Meeting the customer’s needs is essential for an organisation to be successful.

Who is my customer?

Customers usually fall within two categories, internal and external:

Internal Customers

Internal Customers are those who are internal to the organisation and could include management, employees, or any department in the business. Considering the process looking to be improved by the project, who in the organisation with the output of that process go to, they are your internal customer.

Example: A waiter in a restaurant take an order from a customer and passes the information of the order to the kitchen for a chef to prepare the food. In this process, the chef in the kitchen is the customer as they receive the information regarding the other.

External Customers

External customers are those who are external to the organisation and will be the end user of the product or service that you offer or have a professional interest in the organisation such as Regulators i.e., Health and Safety officers and Food Standards agencies ensuring the product or services are meeting set standards.

Process map of the voice of the customer
Process map of the voice of the customer

Why is the voice of the customer important?

In the context of improvement projects, if you want your process improvement project to be successful you must consider the voice of the customer both internal and external. Just because internal customers don’t have a choice in picking their supplier when processes are internalised in the organisation does not mean what they want does not matter.

When making improvements to a process it is important to identify the customer and identify what are their needs from this process as their supplier. Identifying and improving the process to meet their needs will increase the success of the project and reduce the risk of implementing improvements that cause a problem further along in the internal business process which could cause the improvement to be reversed as it resulted in issues such as increased process time or rejects and defects later in the process.

Additionally, identifying your customer’s needs can identify further improvement opportunities than expected if included in the project and could clarify areas of the current process which are unnecessary as they add no value to the customer, therefore, reducing unnecessary process steps.

The same can be said for understanding the voice of external customers, are there any features included in the product that the customer does not need and increase the cost of the product to no benefit of the end user?

Example: A business that produces cardboard boxes 300 millimetres cubed with a specification tolerance of +/- 5 millimetres anything outside of this is classed as a defect, and an estimated 5% of all boxes produced go to waste as they are up to +/- 10 millimetres. However, the customer is happy to accept boxes with a specification of 300 millimetres cubed with a tolerance of +/- 12 millimetres, however, the supplier did not ask the customer and is scrapping 5% of their products which would have been deemed acceptable to the customer. This is classed as waste when exceeding the customer’s expectations.

So when considering the customer it is important to know:

  • Why your customers need you
  • What you can do to help your customers
  • What your customers are looking for
  • What are their interests and behavioural patterns are

If you want to succeed in your role, you must listen to your customers.

MCDVoice – Voice of customer example

McDonalds Receipt
McDonald’s Receipt

Every sale for Mcdonald’s is an opportunity to get some McFeedback, going to mcdvoice.com and inputting the survey code tells Mcdonald’s information about the customer location, order, etc. The customer is then able to answer questions providing further information about their experience.

Imagine how much feedback Mcdonald’s can collect with a simple low-cost process and get priceless data about their customer’s experience they are then able to conduct voice of the customer analysis and identify any issues that need to be addressed or improvements that can be made based on the voice of the customer research.

Google reports between 100k and 1 million searches a month for MCDVoice so Mcdonald’s is certainly collecting a lot of feedback.

How to determine the customer needs?

So now you know who your customers are and why their needs are important, you must be wondering how I can effectively identify my customer’s needs.

Below is a clear four-step process to help you determine what your customers want.

  • Step one – Identify your customers
  • Step two – Gather information about your customers
  • Step three – Analyse the information about your customers
  • Step four – Determine your customer’s needs.

Below we will explain in more detail how this can be done, what useful tools to support each step and what the objectives should be.

Step One – Identity Customers

The first step in determining the customer’s needs starts with identifying, who are the customers. This has been covered previously as part of the article on SIPOC extensively and you can find a great level of detail on the topic there.

The SIPOC identifies the process looking to be improved but also the suppliers, inputs, outputs and customers. With the completion of a SIPOC you should have a complete understanding of who the customers are in the process.

The objective of this stage is to assess the needs of the business and to identify who the customers are so that you can conduct valid voice of customer research.

Step Two – Gather Customer Information

Now that you know who the customers are, the second step is to gather customer information which can seem overwhelming if you have a lot of customers but there are a range of methods this can be done with each having its own benefits and drawbacks

  • Customer interviews
  • On-site customer surveys
  • Live chats
  • Social media
  • Net Promoter Score
  • Feedback forms
  • Focus groups

Selecting the right VOC Tools

Feedback FormLowCan gather data from multiple sources.   Suitable for numeric dataRequires a customer to decide to leave feedback, could skew results toward feedback from people with strong positive or negative views
Phone SurveyHighCan randomly select which allows conclusions for the entire populationRequires a lot of input effort to get a relevant sample site   Unwanted phone calls to customers can be annoying
Mail SurveyMediumCan randomly select allowing for conclusions for the entire population Can be lower cost than phone calls or in-person surveysReliant on the customer returning the feedback for it to count. Most likely not going to receive a high percentage of feedback so the sample size would need to be large.
Social MediaLowCan collect feedback on an ongoing basis   Able to ask questions on the fly The least expensive way to collect VOCRequires an established social media presence engaged with posts   Reliant on mostly those who are positive about your brand and follow you. Negative customers less likely to engage with social media
Focus groups in personHighAllows facilitators to seek more in-depth answers and immediate feedbackLimited to data from local customers or those willing to travel   Can’t use data to make assumptions about general population   Customers less likely, to be honest in person
Focus Groups onlineLowAllows facilitators to seek more in-depth answers and immediate feedback   Does not require travelCan’t use data to make assumptions about the general population  
User or beta testingHighProvides detailed feedback about a specific product, service or processTakes time and requires experienced users or testers.

The choice of medium for collecting the voice of customer data very much depends on how many customers you need to speak to, to get a statistically representative sample and if you are looking to collect qualitative or quantitative data on your customers.

Note: Survey Monkey has a Sample size calculator to help you calculate how many customers you need to speak to for a statistically relevant sample.

Example of survey monkey calculator being used
Example of survey monkey calculator being used

Qualitative data is information that cannot be counted, measured, or easily expressed using numbers. This could be written or verbal detailed feedback about a customer’s experience. This data can usually be visualised in infographics and word clouds

Quantitative data is always numerical data and can easily be analysed in a database using statistical and mathematical methodologies. This data can usually be visualised well in charts and graphs.

It is important to understand what information/data you need to collect from your customer to then identify the best method and the correct questioning to collect data on your customers. There are so many options from binary yes/no questions to “Tell me about your experience” questions and “rate your experience from 1 to 10” scoring that you need to understand what type of data output will help you best with understanding your customer’s needs you have to ensure you create the correct voice of the customer methodology for collecting data.

The objective of this step should be to listen to VoC and obtain useful and valid information about your customers with will be useful for Voice of customer analysis in the next step.

Step Three – Analyse Customer Information

The third step is to analyse the voice of the customer, you will likely have collected a good amount of information at this point and need to effectively analyse it to understand what the customers are saying.

There are a range of tools and techniques that can be used to analyse and better understand the voice of the customer at this stage including the Kano model and Affinity Diagrams

Affinity Diagram

Affinity Diagrams are useful for collecting feedback from the voice of your customer and grouping the feedback by affinity and understanding what themes of feedback from your customers can be identified.

Example of an affinity diagram with quality and cost
Example of an affinity diagram with quality and cost

The Kano Model

The Kano Model is a useful tool to prioritise the customers’ needs based on excitement, performance, and basic needs. The model focuses on the fact that basic needs must be met before performance and excitement factors will positively impact the customer.

The Kano model explaing and priortising the customer needs
The Kano model explains and prioritising the customer needs

Note: It is important that customers decide what is a priority and not the business as the customer knows best in terms of what is most important to them about your product or service.

The objective of this step is to understand what the customers are saying in their language and prioritise their feedback.

Step Four – Determine Customer Needs

The fourth and final step is to determine the customer needs or critical customer requirements and convert them into Critical to quality (CTQ) requirements that can be measured. We need to convert the customers’ needs into critical quality requirements as the customer tends to express what they want in general, vague and unmeasurable terms.

So for this, we need to:

  1. Capture the customers’ requirements, feedback, and complaints
  2. Understand what the underlying issue is
  3. Decide how we can measure it
  4. Define the defect

Example: A customer orders a pizza at a restaurant, but the customer provides feedback or a complaint that the “order took too long”, therefore the underlying issue is the customer waited too long for food. How do we measure how long is too long? We could conduct some data collection to understand what a reasonable amount of time to wait for a food order is or benchmark other restaurants with good levels of service.

A measurable CTQ here could result that customers must receive their food orders within 15 minutes from the time of placing the order. This can now be a measurable KPI, did the customer receive their order in 15 minutes? Any order that takes longer than 15 minutes will be classed as a defect.


In Conclusion voice of the customer is an essential process to understand what your customer needs are from the product, process, or service. These need to be identified, understood, prioritised and made into measurable Critical to Quality (CTQ) factors. This support the project team in understanding the customer requirements that should be met when making improvements to ensure the improvement project does not negatively impact the customer.

What’s next?

Now that you have understood the requirements of the customer the next step is to understand how the process is actually being done in order to identify wastes or issues with the current state. Check out the next article in this Lean Six Sigma Yellow Belt series on Process Mapping.


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Daniel Croft

Daniel Croft is a seasoned continuous improvement manager with a Black Belt in Lean Six Sigma. With over 10 years of real-world application experience across diverse sectors, Daniel has a passion for optimizing processes and fostering a culture of efficiency. He's not just a practitioner but also an avid learner, constantly seeking to expand his knowledge. Outside of his professional life, Daniel has a keen Investing, statistics and knowledge-sharing, which led him to create the website www.learnleansigma.com, a platform dedicated to Lean Six Sigma and process improvement insights.

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