Voice of Customer, Voice of Client (VOC)

Photo by  Sylvain Kalache

Have you ever spent a lot of time and a lot of effort creating a product or a service only to find out it’s not what the client wanted? Quite deflating, isn’t it? And sometimes that kind of waste could be fatal to a company.

Many companies think they know what their clients want. Very few take the time to investigate and confirm. In the Six Sigma DMAIC process we don’t want to guess, we want to be certain. To do so we reach out to our customers, clients, partners and suppliers to make certain we are hearing what is really important to them.

Why is Voice of Client Important?

In short, soliciting voice of client is important because without customers you have no company. The best way to get higher customer satisfaction is to ensure you are delivering what they want when they engage you.

The better you deliver against customer requirements the higher the customer satisfaction. Very satisfied customers are loyal and may even help to promote your products and services.

Many people fall into the trap of assuming based on their experience what their customer. To truly understand, you have to ask and clarify continually. Your customers’ wants and needs are every changing. If you do not know what your customer wants, how can you possibly know if you are delivering what is expected of you.


Customer value

Why voice of client is important.

Why Solicit Voice of Client?

We want to solicit voice of client so we can follow the principles of continuous improvement. For example, you would want to get better at the post-purchase experience so your company can increase sales by shunting customers into the loyalty loop rather than the less stable active research loop.

How do we get Voice of Client?

evolution of voice of client

Photo by Infopark AG


Data collection is covered later on in the Measure phase of DMAIC. However, what we want to obtain is the expectations of the customers, as they state it in their own words.

Some examples might be:

  • High quality
  • Great service
  • Quick delivery
  • Flexible options
  • Durable goods

Proactive vs Reactive Voice of Client Collection

Voice of Client data collection can be thought of in 2 ways; Proactive and Reactive.


It’s always better to be proactive rather than reactive in life. Same principal applies to gathering Voice of Client. In the proactive model you are reaching out to people before there is a problem or the task is complete. Here are a few ideas:

  • “Go to the Gemba” – get out on the floor and watch what is happening in real life.
  • Use mock ups and beta versions to test with volunteers before getting in to production.
  • Send out surveys to a potential customer base.
  • Interview clients and partners on how they see your processes working. Just ask their opinions. “What would you say if we offered X?” “How does this approach sound to you?”
  • Model office. Running simulations is a great way of getting advance data.


Just because proactive is favored over reactive doesn’t mean there is no value in reactive sources. In some cases gathering reactive data may be very easy. Your organization likely has great stores of reactive data. Here are examples;

  • On-line feedback – You may have comments on your website or letters to the editor. There are review sites and social media comments. If you created an iPhone app, iTunes keeps a rich array of user feedback. Restaurants can leverage Yelp. Service providers can use Angie’s List. Many, many options here.
  • Customer service logs – if people are returning a produce or calling in for support you can easily quantify and stratify that data to find the most common issues.
  • You can always send a survey right after performing a service or making a sale.
  • Net Promoter Scores – this is a great concept. Wonderful article describes this here.

Now that we have Voice of Client we can move on to translating that data into specific Critical to Client measures so we can take action on improving them. Remember that the Voice of the Customer is the customer’s specification limits.

Voice of Customer Videos

Six Sigma Black Belt Certification Voice of Client Questions:

Question: Which of the following is most important in evaluating and understanding design intent? (Taken from ASQ sample Black Belt exam.)

(A) Identifying the functional requirement
(B) Brainstorming failure modes
(C) Conducting computer simulations
(D) Developing FMEA

Answer: (A) Identifying the functional requirement has to be the first stop because it orients you to what the design was attempting to solve. Options B and D concern risk and c is related to predictive analysis.

Question: The most important aspect of functional requirements is that they: (Taken from ASQ sample Black Belt exam.)

(A) describe a single, measurable performance
(B) describe how a product or service should operate
(C) be traceable to the voice of the customer
(D) provide upper and lower performance limits

Answer: (C) be traceable to the voice of the customer. Functional requirements must be traced to the voice of the customer or else there is no point in having them. Not all requirements are directly measurable ruling out options a and d. The functional requirements will provide insight to what the performance limits should be but will rarely explicitly state them.

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