The McDVoice survey at www.mcdvoice.com is a customer feedback program designed to improve McDonald's services. To participate, you must meet certain requirements: you need a recent purchase receipt from McDonald’s with a survey code printed on it. The survey must be completed within seven days of your visit, and participants must be 18 years or older. Each receipt can only be used once for the survey. Additionally, the survey is limited to residents of the country where the purchase was made. Upon completion, you may receive a validation code for discounts or free menu items on your next visit.