Share of Voice in advertising is a measurement model within advertising. Share of voice measures the percentage of media spending by a company compared to the total media expenditure for the product, service, or category in the market. For example, if an electronics brand were to invest $5,000,000 advertising their latest e-reader, but $100,000,000 worth of advertising was spent advertising e-readers across the entire market for this shared category, then the 5 million dollar investment would equal a 5% share of voice.
Share of Voice can be calculated by taking your advertising spend and dividing it by the total of all market advertising spend for the same type of product or category. [1]
Share of Voice is used to "represent the relative portion of ad inventory available to a single advertiser within a defined market over a specified time period."[2]