Microsoft Invest - Listen-through targeting
Based on historical listen-through rate data across several dimensions of the ad call, Microsoft Advertising has developed a methodology for determining, pre-auction, the percentage probability of audio completion once the ad is delivered to the page.
Listen-through targeting allows traders to target audio inventory with a projected percentage of audio completions. The listen-through rate is defined as the number of audio completions / number of ad impressions for a particular line item.
You can opt to buy only impressions that have a certain percentage predicted audio completion by selecting the Listen-Through Rate Threshold checkbox in Line Item > Viewability & Environment Targeting, and entering a percentage value.